From 1 October 2026, the rules concerning tax overpayments resulting from amended tax returns will change. In many cases, a separate application for confirmation of an overpayment will no longer be required.
An amended return may itself initiate the proceedings
Until 30 September 2026, a taxpayer, remitter or collector filing an amended return after the statutory filing deadline and showing an overpayment generally had to submit a separate application for confirmation of the overpayment.
Amendments filed before the original filing deadline did not require such an application.
From 1 October 2026, the Act of 29 May 2026 amending the Polish Tax Ordinance and certain other acts applies. The amendment repealed Article 75 § 3 and § 3a of the Tax Ordinance and introduced Article 165 § 8a.
Where an overpayment results from an amended return filed after the deadline, a separate application for confirmation of the overpayment will no longer be necessary. The date on which the amended return is filed will be treated as the date on which the proceedings are initiated.
The filing date will affect the refund and interest
The new approach simplifies the procedure, but it also has procedural consequences.
The date on which the amended return is filed will determine the time limit for refunding the overpayment and, where applicable, the period relevant for interest on the overpayment.
In practice, the amended return itself will therefore play a more significant procedural role than before.
Overpayments above PLN 10,000 will require written justification
At the same time, the amendment introduces a new formal requirement.
Where an amended return shows an overpayment exceeding PLN 10,000, it must be accompanied by a written explanation of the reasons for the amendment, in accordance with Article 81 § 2b of the Tax Ordinance.
Failure to provide the explanation will not invalidate the amended return. According to the explanatory memorandum, however, the tax authority should request completion of the missing justification, and the refund may be withheld until the deficiency is remedied.
Where the overpayment does not exceed PLN 10,000, providing such justification will remain optional.
Transitional provisions are also important
Taxpayers should also pay attention to the date on which the amended return was filed.
Where the amendment was submitted before 1 October 2026, the previous rules will continue to apply to the confirmation, refund and interest relating to the overpayment.
The new regime will therefore apply to amended returns filed from the date on which the new rules enter into force.
Refusal to confirm the overpayment may render the amendment ineffective
The amendment also introduces an important consequence where the tax authority reaches a negative decision.
If the authority refuses to confirm the overpayment, the amended return will not produce legal effects. Under Article 81b § 2a of the Tax Ordinance, the authority will indicate in the reasoning of its decision that the amended return is ineffective.
The key conclusion is straightforward: from 1 October 2026, an amended return may itself initiate overpayment proceedings, but where the overpayment exceeds PLN 10,000, a written explanation of the reasons for the amendment will be required.
Please contact us if your organisation requires support in preparing an amended tax return or handling an overpayment procedure.
We support businesses in preparing amended tax returns, assessing overpayment claims and handling proceedings concerning confirmation and refunds. We also assist in preparing the written justification required where the overpayment exceeds PLN 10,000.
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