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Additional works and contract modifications in Polish public procurement — Article 455 of the Public Procurement Law

Ten artykuł jest dostępny także po polsku. Dieser Beitrag ist auch auf Deutsch verfügbar.

In Polish public contracts, a dispute over additional works is fought on two fronts at once: the civil-law front (were the works covered by the lump sum?) and the procurement front (was the contract allowed to be modified?). Awarding entities often refuse payment with a single sentence: „contract modifications are prohibited”. In reality, Article 455 of the Polish Public Procurement Law describes four legal gateways with concrete limits — 15 % and 50 % of the contract value — and the case law has for years ordered public bodies to pay for work they received even where a valid amendment was never signed. Below is the full mechanism: where the prohibition comes from, how to exit it legally, what the sanctions are, and how settlement works when the works were carried out without a contractual basis.

Where the prohibition on modifications comes from

The starting rule reads: a material modification of a concluded contract requires a new award procedure (Article 454(1) of the Public Procurement Law of 11 September 2019, consolidated text Dz.U. 2026 item 793, „PPL”). Its pedigree is the case law of the Court of Justice of the EU. In pressetext, the Court explained when a change to a running contract is in substance a new award that should have been opened to competition again:

„An amendment to a public contract during its currency may be regarded as being material when it introduces conditions which, had they been part of the initial award procedure, would have allowed for the admission of tenderers other than those initially admitted or would have allowed for the acceptance of a tender other than the one initially accepted.”

— judgment of the CJEU of 19 June 2008, C-454/06 pressetext Nachrichtenagentur, para 35 (official English text)

The Court added that an amendment is also material when it extends the scope of the contract considerably to encompass services not initially covered (para 36) and when it changes the economic balance of the contract in favour of the contractor in a manner not provided for in the initial contract (para 37). This test was taken over by Directive 2014/24/EU (Article 72, OJ EU L 94 of 28 March 2014) and, following it, by Article 454(2) PPL, under which a modification is material if it makes the character of the contract materially different from the original one — in particular where it introduces conditions that would have opened the procedure to other contractors or other tenders, upsets the economic balance in favour of the contractor in a way not provided for in the contract, considerably extends or reduces the scope of performance, or replaces the contractor outside the permitted cases.

The ratio is worth remembering: the provision protects competition from the tender — that is, other bidders and the fairness of comparing offers. It is not a tool for the awarding entity to receive construction works for free. That difference of purpose returns in every thread below.

A short history of old Article 144 — why awarding entities say „not allowed”

The refusal reflex has historical roots. Under the previous statute of 29 January 2004, old Article 144(1) in the version in force until 24 October 2008 allowed only modifications favourable to the awarding entity or resulting from circumstances that could not have been foreseen — a trace of that state is still visible in the judgment of the Polish Supreme Court of 21 February 2013, IV CSK 354/12, quoted below. After the 2008 amendment, a material modification was permissible only where the awarding entity had provided for it in the contract notice or the terms of reference and had defined its conditions. In practice, awarding entities simply did not write modification clauses in — they thereby gained price certainty, and contractors lost any contractual route to settle unforeseen works. Only the amending act of 22 June 2016 (Dz.U. item 1020), implementing Directive 2014/24/EU, introduced a catalogue of statutory grounds for modification independent of the awarding entity’s foresight. The current Articles 454–455 PPL took over that model.

The practical conclusion: when an awarding entity claims that „procurement law does not allow us to pay”, it is usually describing the legal position of a decade ago. Today’s statute provides legal grounds for an amendment that do not depend on whether a modification clause was written into the contract.

The map of legal modifications, with limits

Two safety valves complete the system. First, for modifications under points 3 and 4 the awarding entity may not make successive modifications in order to circumvent the statute, and after making the modification it publishes a contract modification notice (Article 455(3) PPL) — a „quiet” amendment therefore breaches the procedure even where it is substantively justified. Second, if the contract contains price adjustment clauses, the permissible value of a modification is calculated against the adjusted price (Article 455(4) PPL) — the 50 % and 15 % limits are thus counted from the updated price, not the historical one.

Review clauses: precision or nothing

The most common mistake with clauses under Article 455(1)(1) PPL is vagueness. A provision that „the parties allow a change of deadline and remuneration in the event of adverse weather conditions” does not meet the requirement of clarity and precision. Already in the guidance of the Public Procurement Office on the predecessor of this provision (old Article 144(1)(1) of the 2004 statute) it was explained that a weather clause requires defining the type of precipitation, its intensity and duration, and the concrete consequences for the deadline and the remuneration — otherwise it provides no basis for modifying the contract.

This casuistry has its price, however, and it should be named openly. Construction is too dynamic a process for it to be possible to describe „unambiguously” in advance every event that will force a correction of scope, time or price. An overly general clause will not work, and a complete catalogue cannot be drawn up. A well-drafted review clause therefore does not displace the statutory gateways of points 3 and 4 — they exist precisely for events not provided for in the procurement documents.

Additional works from the existing contractor (point 3)

Article 455(1)(3) PPL is the direct basis for commissioning additional works from the contractor already present on site. There are three conditions: the additional works have become necessary, a change of contractor cannot be made for economic or technical reasons (for example, the requirement of interchangeability or compatibility with what has already been built), and entrusting them to someone else would cause substantial inconvenience or a substantial increase of costs. The limit: a price increase of no more than 50 % of the original contract value for each successive modification.

This basis has an instructive history which shapes the case law to this day. Until 28 July 2016 its counterpart was the single-source award of „additional contracts” (old Article 67(1)(5) of the 2004 statute). In payment disputes, however, courts dismissed claims based on that provision with a characteristic reasoning: since the remuneration was a lump sum, the works necessary to complete the structure were „covered by the main contract” — so there were no additional contracts and nothing to settle. So held, for example, the Court of Appeal in Białystok in a case concerning works on residential buildings (judgment of 6 November 2015, I ACa 542/15, LEX No. 1934427), adding a warning worth knowing before every tender:

„the claimant, as a professional, entering a tender based on the provisions of the public procurement law, had not only the right but in fact the duty to acquaint itself in detail with the documentation concerning the investment and at that stage should have striven to remove all emerging doubts, and only then submit a tender or refrain from submitting it.”

— judgment of the Court of Appeal in Białystok of 6 November 2015, I ACa 542/15, LEX No. 1934427, translation by the author

The mechanism of that reasoning — the lump sum swallows everything necessary — is analysed critically in our article on additional works under lump-sum remuneration: a lump sum fixes the price, not the scope of performance, so works going beyond the scope described in the documentation do not become „covered by the contract” merely because they are needed. On the procurement plane the conclusion is that the classification of the works determines the basis for the amendment — and whether the 50 % limit applies at all.

Unforeseeable circumstances (point 4) — and the design-error trap

The fourth basis is the natural candidate for unforeseen ground conditions, collisions with uncharted infrastructure or changes of law:

„where the necessity of modifying the contract, including in particular a change of the amount of the price, is caused by circumstances which the awarding entity, acting with due diligence, could not have foreseen, provided that the modification does not alter the general character of the contract and the price increase caused by each successive modification does not exceed 50 % of the original contract value.”

— Article 455(1)(4) PPL, translation by the author

The key words are „acting with due diligence”. Unforeseeability is assessed objectively and refers back to the stage of preparing the procedure. In the case law of the administrative courts — on the predecessor of this regulation — it was held that errors in the building design or the technical specification, as well as the unjustified omission of some works, do not justify a contract modification, because unforeseeability turns on whether the awarding entity exercised diligence in preparing the investment process (so the Voivodeship Administrative Court in Łódź in its judgment of 29 May 2014, III SA/Łd 332/14, LEX No. 1532035). It is irrelevant that the design was drawn up for the awarding entity by an external designer — the designer’s error burdens the awarding entity’s sphere.

For the contractor this yields a conclusion that tends to surprise: the more evident the awarding entity’s error, the harder it is to obtain a legal amendment. Defective documentation is not an „unforeseeable circumstance” within the meaning of point 4, because with diligent preparation it could have been avoided. The amendment must then be built on another basis (a review clause, point 3, a low-value modification), and if the awarding entity refuses — the claim proceeds down the civil path: through unjust enrichment or through liability for defective design documentation. In our view this state of the law deserves criticism: what should decide the settlement of works is whether the awarding entity provided for them in the description of the subject matter of the contract, not whether it objectively could have foreseen them. At the moment of submitting the tender, the contractor does not know whether the contract was described correctly and has no influence over it — yet it is the contractor who bears the financial consequences of carelessness on the other side.

Sanctions for stepping outside the statutory frame

The statute is explicit here: a modification of the contract is subject to annulment if it was made in breach of Articles 454 and 455, in which case the contractual provision in its wording prior to the modification applies (Article 458 PPL). The President of the Public Procurement Office may apply to the court for annulment of the modification, and that right expires only 4 years after the modification was made (Article 459 PPL). Independently of this, the awarding entity may withdraw from the contract in the part affected by the impermissible modification (Article 456(1)(2)(a) PPL), and in extreme cases the annulment of the contract itself comes into play (Article 457 PPL). On top of that comes the personal liability of decision-makers for a breach of public finance discipline: modifying a public procurement contract in breach of the procurement provisions is such a breach (Article 17(6) of the Act of 17 December 2004 on liability for breach of public finance discipline, consolidated text Dz.U. 2025 item 1484).

This explains the caution of awarding entities — but it does not excuse it where the statute expressly provides a basis for the modification. Refusing to use a legal gateway is not „safe”: as we show below, it ends in a lost court case with interest and costs, and those burden the entity’s budget as well.

Written form on pain of nullity

The contract requires written form on pain of nullity, unless separate provisions require a special form (Article 432 PPL). The requirement also covers amendments, because the supplementing or amendment of a contract requires the same form as the statute or the parties provided for its conclusion (Article 77 § 1 of the Civil Code of 23 April 1964, consolidated text Dz.U. 2026 item 795). An oral or e-mail arrangement of additional works with the supervision inspector or a head of department therefore creates no contractual obligation, even if everyone acted in good faith. This is the most common mistake of contractors used to private-sector dealings. A typical course of events is shown by the case that ended with the Supreme Court judgment of 2 February 2011, II CSK 414/10 (LEX No. 738390): the contractor performed additional works for PLN 177,762 and prepared a draft amendment — and the awarding entity simply never signed it. How to record and document works so as not to be left with nothing is the subject of our guide to documenting additional works.

Works performed without a valid amendment: a settlement happens anyway

The nullity of the arrangement does not mean the work is forfeited. The procurement regime does not displace the Civil Code — on the contrary, the statute expressly orders the Civil Code to be applied to public procurement contracts (Article 8(1) PPL). The Supreme Court puts it unambiguously:

„the public procurement provisions do not derogate from the provisions on unjust enrichment, and a claim for the return of the value of construction materials built into the awarding entity’s building in performance of a contract that is invalid for breach of the public procurement provisions is a claim for the return of the value of an undue performance grounded in Article 410 § 1 in conjunction with Article 405 of the Civil Code […]”

— judgment of the Supreme Court of 7 February 2013, II CSK 248/12, LEX No. 1293945, translation by the author

In that case it was established that the awarding entity knew of the extension of the scope of works, that the additional works were performed with its consent, albeit expressed in the wrong form, that they were not included in the terms of reference, and that this happened for reasons attributable to the awarding entity — and that settled the duty to return the value of the works. The line of authority is settled and older than this judgment (see the Supreme Court judgments of 7 November 2007, II CSK 344/07, LEX No. 388844, and of 2 February 2011, II CSK 414/10). The Supreme Court assessed identically the settlement of additional road works performed without an amendment against the background of defective tender documentation:

„since the defendant benefits from the effects of the works performed by the claimant, and the claimant was under no obligation to scrutinise the design supplied to it in order to detect its defects […], one must agree with the appellant that the parties should settle on the basis of the provisions on unjust enrichment. The public procurement statute does not regulate the civil-law consequences of the parties concluding a contract in breach of Article 139(2) of that statute, and Article 139(1) confirms the civil-law character of contracts concluded under public procurement, ordering the provisions of the Civil Code to be applied to them directly.”

— judgment of the Supreme Court of 21 February 2013, IV CSK 354/12, LEX No. 1311808, translation by the author

Three practical caveats. First, what is settled is the value of the enrichment, not the agreed rate — the difference, and the trap of Article 411(1) of the Civil Code, are discussed at length in our article on unjust enrichment on a construction site. Second, before starting disputed works it is worth reserving in writing the return of their value — in II CSK 248/12 the contractor was saved precisely by the finding that it not only performed in execution of an invalid juridical act, but additionally performed with a reservation of return. Third, the claim must be framed consciously from the outset: whoever sues for „contractual remuneration” risks the court being unable to award the same amount as unjust enrichment (so the courts of the lower instances in II CSK 344/07 against the background of Article 321 § 1 of the Code of Civil Procedure — the limits of this procedural trap and its softening by the Supreme Court are discussed in the unjust enrichment article).

Questions about the tender documents: a right that can become a duty

The contractor may ask the awarding entity to explain the content of the terms of reference (Article 135(1) PPL), and the awarding entity must answer. In the case law, however, this right is capable of turning into a duty — with a sanction for the silent:

„[I]n the given circumstances of the public procurement order being placed and accepted, and of the doubts existing on the contractor’s side, Article 38 of the Public Procurement Law constitutes, in conjunction with Article 354 § 2 of the Civil Code, not only a right but also a duty of the contractor to apply to the awarding entity for an explanation of the content of the terms of reference […]”

— judgment of the Supreme Court of 5 June 2014, IV CSK 626/13, LEX No. 1491332, translation by the author

The judgment was rendered on the basis of Article 38 of the previous statute (today Article 135 PPL), in the case of a contractor who failed to ask about a detail essential for performing the contract and paid for it in contractual penalties. Combined with the warning from I ACa 542/15 (the duty to study the documentation in detail before tendering), this yields a clear standard: if you notice an ambiguity in the procurement documents — ask in writing before the deadline for tenders. The question asked and the awarding entity’s answer become part of the material for interpreting the contract, and courts are capable of holding the absence of a question against you years later. The limits of this duty matter, though: it concerns doubts noticeable when reading the documentation through a contractor’s (pricing) eyes, not an audit of someone else’s design — the limits of the review duty under Article 651 of the Civil Code are described separately.

The limits of shifting risk: the tram-track case

The flip side of the duty to ask questions is the awarding entity’s duty to give something to ask about: the subject matter of the contract is to be described in an unambiguous and exhaustive manner, by means of sufficiently precise and comprehensible terms, taking into account the requirements and circumstances capable of affecting the preparation of a tender (Article 99(1) PPL). The National Appeal Chamber (KIO) described the sense of this regulation as follows — against the background of a tender in which bidders were to price, among other things, the correction of works already performed, about whose quality they knew nothing:

„the provisions of the specification may not in any way differentiate the situation of contractors at the stage of submitting tenders and, on the other hand, contractors should not remain in uncertainty as to the scope of the contract to be performed in the future and should be able to calculate the price on the basis of the full subject matter of the contract drawn up by the awarding entity.”

— judgment of the KIO of 27 December 2011, KIO 2649/11, LEX No. 1102065, translation by the author

The loudest test of the limits, however, was the tender of the City of Gdańsk for the reconstruction of tram tracks in Kliniczna Street. The contractual conditions contained sub-clause 1.8, whose fifth paragraph read:

„The Contractor declares that it has acquainted itself with the Design Documentation and the Construction Site and has verified their completeness, accuracy and sufficiency for the performance of the Works and the Contractor’s Documents, and confirms such completeness, accuracy and sufficiency of the Design Documentation for the performance of the Works and the Contractor’s Documents. The Contractor accepts that it shall have no claims whatsoever and expressly waives all possible claims against the Employer in respect of any mistakes, inaccuracies, discrepancies or omissions or other defects of the Design Documentation, including any claims for payment of any increased Costs or payments in addition to the Contract Price, or for an extension of the Time for Completion as a result of such mistakes, inaccuracies, discrepancies or omissions or other defects of the Design Documentation.”

— sub-clause 1.8, paragraph 5 of the contractual conditions, quoted after the judgment of the KIO of 27 April 2011, KIO 806/11, LEX No. 821263, translation by the author

The contractor was thus to confirm in advance the completeness of someone else’s design and waive all claims arising from its defects — including claims for increased costs and extensions of time. The Chamber ordered the clause deleted, and its reasoning remains the model to this day:

„It is difficult to require of a contractor that, before submitting its tender, it should have verified the design documentation (and the construction site) to such a degree as to be able to assess its correctness and the absence of possible errors which may only reveal themselves in the course of carrying out the works.”

— judgment of the KIO of 27 April 2011, KIO 806/11, LEX No. 821263, translation by the author

The Chamber added that provisions of this kind go far beyond the risk inherent in a lump-sum price and infringe old Articles 29(1) and 31(1) of the 2004 statute (today Articles 99(1) and 103 PPL), because they force the contractor to include in the tender price the costs of risks it is unable to assess at the tendering stage. The epilogue was bitter, though: the court hearing the appeal took the opposite view, holding that since the conditions are identical for all bidders, a contractor may simply not submit a tender, and assesses and prices the shifted risk itself (judgment of the Regional Court in Gdańsk of 14 July 2011, XII Ga 314/11, LEX No. 1124956). That position prevailed in practice at the time.

Today the outcome would be different, because the legislature has spoken. The projected contractual provisions may not provide for the contractor’s liability for circumstances for which the awarding entity bears exclusive responsibility (Article 433(3) PPL), and the awarding entity and the contractor are obliged to cooperate in the performance of the contract (Article 431 PPL). A clause shifting onto the contractor the consequences of defects in documentation supplied by the awarding entity collides head-on with that prohibition. It is one of the strongest arguments a contractor has today — both at the stage of an appeal to the KIO and in a later payment dispute.

The requirement that risk be calculable

In our view, public procurement is additionally governed by a requirement that risk be calculable, which we described as a general limit on shifting risk in our analysis of lump-sum remuneration. Freedom of contract (Article 353¹ of the Civil Code) presupposes self-determination of both parties. In a public tender there is no self-determination on the contractor’s side: the conditions are dictated unilaterally by the awarding entity, and the bidder can only accept them or walk away — and walking away from the public procurement market means, for many construction firms, walking away from most of the market altogether. A contractor can rationally assume a risk that is recognisable and capable of estimation, because it can price it and balance it in the tender. Where a contractual template burdens the bidder with every conceivable risk and describes none of them, calculation stops being arithmetic and becomes guesswork.

The scale of the problem is well shown by a practical example: the tender covers the removal and disposal of soil from an excavation, and no contamination tests were carried out. With low contamination, disposal costs tens of złoty per tonne, with heavy contamination — dozens of times more. At 10,000 tonnes, the „spread” of the risk stretches from several hundred thousand to over a dozen million złoty. No bidder can price such an item other than randomly: whoever adds a buffer loses the tender to the one who gambled. A provision shifting so undefined a risk is in our assessment indefensible — in public procurement it collides with Articles 99(1) and 433(3) PPL, and on the civil plane with the limits of freedom of contract (Article 353¹ in conjunction with Article 58 § 2 of the Civil Code). The measure of the permissibility of shifting a risk should be whether the bidder could reliably calculate it on the basis of the information made available.

Price adjustment: the obligatory clause and what needs no amendment

A contract for construction works, supplies or services concluded for longer than 6 months must contain provisions on the rules for changing the contractor’s remuneration in the event of changes in the prices of materials or costs connected with the performance of the contract (Article 439(1) PPL). The statute requires, among other things, that the contract specify the level of price change that entitles a party to demand an adjustment, the method of determining the change of remuneration and its maximum value (Article 439(2) PPL), and a contractor whose remuneration has been adjusted must adjust the remuneration of its subcontractors accordingly (Article 439(5) PPL).

It is worth knowing that a well-drafted adjustment clause operates without any amendment. The Supreme Court assessed in this way sub-clause 13.7 of the FIDIC conditions (adjustments for changes in legislation) in a contract concluded under public procurement:

„the occurrence of those circumstances was not a basis enabling the parties to modify the contract in accordance with § 13 of the contract under the rules following from Article 144 of the Public Procurement Law, but caused an automatic change of the amount of the agreed remuneration without any need to modify the contract.”

— judgment of the Supreme Court of 22 October 2014, II CSK 773/13, LEX No. 1607466, translation by the author

The automatism has enormous practical value: the contractor does not have to wait for the awarding entity’s goodwill over an amendment, because the change of remuneration follows from the contract itself. That is precisely why the shape of the adjustment clause is worth fighting for with questions about the tender documents and with an appeal — after the contract is concluded it is too late.

Judicial correction of the lump sum despite the prohibition on modifications

The prohibition on contract modifications does not close the judicial route. The Supreme Court described the relationship between the two regimes directly — against the background of old Article 144, but the reasoning remains valid for Articles 454–455 PPL:

„Where this provision is adopted as the legal basis for changing the remuneration of a contractor performing construction works on the basis of a contract concluded in the public procurement procedure, Article 144(1) of the Public Procurement Law of 29 June 2004 […] applies only to the extent to which, in relation to Article 632 § 2 of the Civil Code, it determines the permissibility of modifying the contract. A modification of the contract as regards the amount of remuneration will therefore be permissible if it is favourable to the awarding entity or results from circumstances that could not have been foreseen at the time the contract was concluded, while the remuneration will change if the substantive prerequisites set out in Article 632 § 2 of the Civil Code materialise […]”

— judgment of the Supreme Court of 21 February 2013, IV CSK 354/12, LEX No. 1311808, translation by the author

A precise side-note: in this passage the Supreme Court writes of the statute „of 29 June 2004” — an obvious slip, as the previous Public Procurement Law dates from 29 January 2004. The sense of the ruling is, however, unambiguous: the procurement provisions determine when a modification of the contract is permissible, while the substantive prerequisites for increasing the lump sum are assessed under the Civil Code. To the same effect, earlier, the Supreme Court in its judgment of 20 November 2008, III CSK 184/08 (LEX No. 479317): old Article 144 does not stand in the way of modifications based on Article 632 § 2 in conjunction with Article 656 of the Civil Code. The line is in fact older than both twenty-first-century procurement statutes — already under the Public Procurement Act of 10 June 1994 the Supreme Court held that it is the court, in a case for payment for construction works awarded and performed under public procurement, that rules on the justification of contract changes caused by the circumstances indicated in its Article 76 (judgment of 28 June 2000, IV CKN 70/00, LEX No. 42356 — the public awarding entity’s cassation appeal was dismissed).

A model example of an „unforeseeable circumstance” justifying correction is the case of a stadium built on a former landfill, where hazardous waste not included in the procurement documents came to light during the works:

„The Court of Appeal rightly accepted that the necessity of removing waste of this kind was an event that could not have been foreseen, and it led to an extraordinary change of relations.”

— judgment of the Supreme Court of 21 August 2014, IV CSK 733/13, LEX No. 1541191, translation by the author

The prerequisites, the mechanics of „glaring loss” and the real amounts from the case law are discussed in detail in our article on the judicial increase of lump-sum remuneration (Article 632 § 2 of the Civil Code). In the public procurement context one need only remember the sequence: first exhaust the contractual path (the adjustment clause, the bases of Article 455 PPL), and only then the judicial one — the court asks whether the parties could have solved the problem themselves.

„We cannot pay — public finance discipline”

This argument appears in almost every negotiation with a public body and needs defusing, because it cuts both ways. An impermissible contract modification is a breach of discipline (Article 17(6) of the Act on liability for breach of public finance discipline) — but what is also costly for the budget is bringing about a lost court case with interest and costs where the claim was well-founded. The person deciding on payment is personally liable, so without a clear legal basis they will choose litigation over settlement — that is understandable and must be factored into strategy instead of counting on „reasonableness”.

A legal basis for settlement has existed since 1 June 2017: a public finance sector entity may conclude a settlement concerning a disputed civil-law claim where an assessment shows that the consequences of the settlement are more favourable for the entity, the State Treasury or the local government budget than the probable outcome of court or arbitration proceedings (Article 54a(1) of the Public Finance Act of 27 August 2009, consolidated text Dz.U. 2025 item 1483). The assessment of the settlement’s consequences is made in writing, taking into account the circumstances of the case, in particular the merits of the disputed claims, the possibility of satisfying them, and the anticipated duration and costs of the proceedings (Article 54a(2)). The legislature closed the loop on the liability side: performing a binding settlement that meets these requirements does not constitute a breach of public finance discipline (Article 5(4) of the Act on liability for breach of public finance discipline). A written assessment showing that the settlement is more favourable than the probable outcome of the dispute is therefore a shield for the decision-maker, not a risk. The practical takeaway for the contractor’s counsel: build the settlement proposal from the outset so that it hands the other side the material for the favourability test — with a calculation of interest, litigation costs and a realistic assessment of the litigation risk.

Two perspectives

To contractors we advise: ask about ambiguities before tendering (Article 135 PPL) and keep proof of the questions, report the necessity of works formally, demand a position in writing and point the awarding entity to the concrete basis for an amendment under Article 455 PPL together with the limit calculation. For disputed works — a written reservation of the return of their value before starting. To awarding entities: well-drafted review and adjustment clauses cost little and allow you to manage legally what will happen on site anyway. Refusal „just in case” does not protect the budget, because the extra-contractual settlement will happen regardless — only with interest, litigation costs and years of dispute. Both sides win on documents and procedure instead of corridor arrangements — on the scope of performance covered by the lump sum see also our analysis of what lump-sum remuneration covers.

Frequently asked questions

May the awarding entity commission additional works from the existing contractor without a new tender?

Yes — Article 455(1)(3) PPL provides for this expressly, with a limit of 50 % of the original contract value for each successive modification, and smaller changes fit within Article 455(2) PPL (up to 15 % in aggregate for construction works). The conditions are the necessity of the works and the impossibility of changing the contractor for economic or technical reasons. A refusal without analysing these bases is usually premature.

We performed works on the oral instruction of the supervision inspector. Are we owed anything?

There is no contract in that (Article 432 PPL), but the case law consistently grants the return of the value of the works as an undue performance (Article 410 § 1 in conjunction with Article 405 of the Civil Code), especially where the awarding entity knew of the works, consented to them and benefits from them. What matters is the evidence of the commissioning, scope and value of the works and a written reservation of return — details in the unjust enrichment article.

Is an impermissible amendment void by operation of law?

Structurally it is „subject to annulment” (Article 458 PPL), and the previous wording of the contract returns in place of the annulled modification. The President of the Public Procurement Office may seek annulment of the modification within 4 years (Article 459 PPL). That is why an amendment should from the outset be seated on the proper basis under Article 455 PPL, stated in its recitals.

The awarding entity claims a clause in the tender documents shifts the entire risk of documentation errors onto us. Is that effective?

Such a clause collides with the prohibition of Article 433(3) PPL and with the duty to describe the subject matter of the contract unambiguously and exhaustively (Article 99(1) PPL). It is most effective to challenge it by an appeal to the KIO while the procedure is still running. If the contract has already been concluded, what remains is to plead its ineffectiveness in the payment dispute — with the argument that the contractor could not price a risk that no one described to it.

Despite the prohibition on modifications, can the lump sum be increased by a court?

Yes. The case law holds that the procurement provisions determine only the permissibility of a contractual modification, while the substantive prerequisites of a judicial increase are assessed under Article 632 § 2 of the Civil Code (IV CSK 354/12, III CSK 184/08). It is necessary to show an unforeseeable change of relations and the threat of a glaring loss — the mechanics and the case law are discussed in a separate article.

The awarding entity wants a settlement but fears public finance discipline. What can be done?

Point to Article 54a of the Public Finance Act: a settlement is lawful if a written assessment shows that its consequences are more favourable than the probable outcome of litigation, and performing such a settlement is not a breach of discipline (Article 5(4) of the Act on liability for breach of public finance discipline). A well-prepared settlement proposal contains ready material for that assessment.

The works became necessary because of an error by the awarding entity’s designer. Which gateway of Article 455 PPL works?

Paradoxically, not the „unforeseeable” one: the awarding entity cannot classify errors in its own documentation as circumstances it could not have foreseen with due diligence. What comes into play is a review clause (if one was provided), additional works under point 3, or a low-value modification under paragraph 2. If the awarding entity refuses an amendment, the claim runs through unjust enrichment and, independently, through liability in damages for the defective documentation.

Quotations from Polish judgments and legislation have been translated by the author unless indicated otherwise. All translations are unofficial. The Polish texts are authoritative.

State of the law: 5 September 2026.

Author: Artur Barczewski PhD — Polish attorney-at-law (radca prawny), conducts construction payment disputes for contractors and employers alike. About the author · Discuss your case →