Changing equipment parameters after the contract is signed requires an annex – even if the new device still meets the requirements of the description of the subject matter of the contract (OPZ). The contractor is bound not only by the OPZ but also by the content of its own bid. The good news: if the conditions of Article 455 of the Public Procurement Law (PPL) are met, such an amendment to a public procurement contract does not require a new tender.

A practical example

A university purchases a disk array in an open tender. The OPZ requires SSD drives with a capacity of no less than 3.84 TB and a total usable capacity of at least 200 TB.

In the technical parameters form, the contractor specified 7.68 TB drives and provided a specific catalogue number for the set. After the contract is signed, it turns out that these drives have a long delivery time. The contractor therefore proposes more 3.84 TB drives, so that the total capacity remains unchanged.

The new configuration meets the OPZ. Can the contractor simply deliver it?

Compliance with the OPZ is not enough – the bid is binding too

Public procurement contracts usually provide that the subject matter is to be performed „in accordance with the OPZ and the Contractor’s bid”. A parameter entered in the technical form then becomes part of the performance to which the contractor has committed.

It does not matter that the contracting authority specified only a minimum. If the contractor declared more and indicated a specific model, delivering a different model is an amendment to the contract, not its performance.

The consequences of delivering without agreement can be severe: refusal of acceptance, a demand to replace the equipment, penalties for delay, and even withdrawal from the contract due to a delivery that does not conform to the contract.

Why is an annex required?

Most contracts concluded under the PPL stipulate that any amendment requires an annex in written or electronic form, under pain of nullity. This also applies to non-material changes.

Consent expressed by e-mail by the contract coordinator or an acceptance report signed „without reservations” will not replace an annex. Persons designated for day-to-day contact are usually not authorised to amend the contract – it is worth checking this in its wording.

Is such an amendment permissible under the PPL?

As a rule, a material amendment to a contract requires a new procedure (Article 454(1) PPL). However, the Act provides for exceptions in Article 455 PPL. In the situation described, two of them may apply.

Review clause (Article 455(1)(1) PPL). Many contracts allow the model or type of device to be changed when the indicated product is unavailable and the new one meets the contracting authority’s requirements. Unavailability must be demonstrated, preferably by a statement from the manufacturer or distributor. Convenience or lower cost on the contractor’s side is not enough.

Unforeseeable circumstances (Article 455(1)(4) PPL). Where the contract does not contain an appropriate clause, the amendment is permissible if all of the following conditions are met:

• the need for it results from circumstances which the contracting authority, acting with due diligence, could not have foreseen;
• it does not alter the overall nature of the contract;
• the price increase resulting from each successive amendment does not exceed 50% of the value of the original contract.

These circumstances must be extraordinary and objective, e.g. a model being suddenly discontinued or a supply chain being disrupted after the contract was concluded. Ordinary supplier delays, price fluctuations or the contractor’s commercial decisions fall within normal contractual risk and do not satisfy this condition. Unforeseeability is assessed from the perspective of a diligent contracting authority, so the contractor must provide it with material that justifies it.

How to change equipment parameters – guidance for contractors

The following guidance is addressed to a contractor who wishes to deliver equipment other than that offered.

1. Act immediately – inform the contracting authority of the problem as soon as it arises; contracts usually require this, and the time needed for an annex counts towards the performance deadline;
2. Submit a written request for an annex – indicate the legal basis: the contractual clause or Article 455(1)(4) PPL, if the cause is extraordinary, unforeseeable circumstances;
3. Attach evidence – the manufacturer’s statement on the unavailability of the model, new catalogue numbers of the devices and service packages, documentation confirming each OPZ parameter that the change may affect (usable capacity, performance, rack dimensions);
4. Ensure economic balance – show that the cost does not change, or propose an equivalent;
5. Remember EU funding – in EU-funded projects the contracting authority must document the basis for the amendment for audit purposes, so a well-prepared request will make it easier for it to give consent.

Summary

A „minimum” parameter in the OPZ does not give the contractor freedom after the contract is signed. If you declared more in your bid, delivering less requires an annex – and a well-prepared request.

Frequently asked questions

Can I deliver equipment that complies with the OPZ but differs from my bid?

Not without an annex. You are also bound by the content of your bid, including the declared parameters and the model indicated.

Does an acceptance report without reservations „legalise” the change?

No. If the contract requires an annex under pain of nullity, acceptance will not replace it.

Does changing the device model require a new tender?

No, if the contract contains a review clause or the change was forced by circumstances that the contracting authority could not have foreseen (Article 455(1)(4) PPL).

The above material is for information and educational purposes only – it does not constitute legal advice or an opinion on a specific case. Assessment of a specific factual situation requires individual analysis. Legal status: Act of 11 September 2019 – Public Procurement Law (consolidated text: Journal of Laws of 2026, item 793), in particular Article 454(1) and Article 455(1)(1) and (4).

Dominik Styczyński – attorney-at-law (radca prawny), public procurement law expert representing contractors and contracting authorities before the National Appeals Chamber (KIO)