Late payment interest calculator for Poland - statutory and commercial interest

Polish statutory interest is tied to the National Bank of Poland (NBP) reference rate. Since 5 March 2026 the reference rate is 3.75%, so statutory interest for late payment is 9.25% a year and statutory capital interest 7.25%. Commercial interest for the second half of 2026 is 13.75%.

Civil Code rates change on the day the reference rate changes. Commercial rates stay fixed for a half-year, based on the reference rate on 1 January or 1 July.

Interest = amount × annual rate × days / 365. Days are counted from the day after the due date up to and including the payment date. If the rate changed in between, each period is calculated separately and added up.

Example 1: an invoice for PLN 10,000 due on 31 March 2026, paid on 30 June 2026. That is 91 days late at 9.25%: 10,000 × 9.25% × 91 / 365 = PLN 230.62.

Example 2: the same amount, due on 31 March 2025, paid on 31 December 2025 (275 days). The reference rate changed six times in that time, so late payment interest is calculated in seven periods (from 11.25% down to 9.5%), giving PLN 782.87. The calculator shows each period in a table. It uses a 365-day year, also in leap years, as most Polish courts and debt collection software do, and rounds each period to the grosz.

Commercial late payment interest applies when both parties are businesses (or one is a public body) and the debtor fails to pay on time. The creditor does not have to prove any loss. Payment terms between businesses should generally not exceed 60 days. On top of interest, the creditor is entitled to compensation for debt recovery costs (Art. 10 of the Act):

• €40 - for an amount up to PLN 5,000,
• €70 - above PLN 5,000 and below PLN 50,000,
• €100 - PLN 50,000 or more.

The euro amount is converted at the NBP average rate from the last working day of the month before the payment fell due. It is due for every late invoice, without a payment demand. This mirrors the EU Late Payment Directive, so foreign suppliers invoicing Polish companies can rely on it too.

• Counting from the due date itself. Interest starts the next day - if the deadline is 31 March, the first day of delay is 1 April.
• One rate for the whole period. In 2025-2026 the reference rate changed seven times (from 5.75% to 3.75%), so longer delays need separate periods.
• Capital interest instead of late payment interest. For late payment you claim late payment interest, 2 pp higher; capital interest is for things like a loan with no agreed rate.
• Commercial interest from a consumer. From a private person you can claim only statutory late payment interest.
• Exceeding the maximum. Contractual late payment interest cannot exceed twice the statutory late payment rate, i.e. 18.5% at 9.25% (Art. 481 § 2¹ Civil Code).

If an employer pays your severance late, the same statutory interest applies - see the severance pay calculator.