Late-payment interest — what you should know
When a counterparty pays late, you're entitled to charge interest. In business-to-business transactions, the default basis is statutory interest for delay in commercial transactions (the Act on Counteracting Excessive Payment Delays). The parties may also apply statutory interest for delay under the Civil Code. Both rates depend on the NBP reference rate.
This calculator computes interest separately for each period a rate was in effect (when the overdue period spans a rate change) — so the result is exact, not averaged.
Three kinds of interest — easy to confuse
In business you'll come across several kinds of interest, each governed by its own rules:
- Commercial for delay in commercial transactions (between businesses and with public entities) — due by operation of law, without any clause in the contract
- Statutory for delay under the Civil Code (Art. 481) — the basic civil interest, applied when the commercial rate doesn't apply
- Tax on arrears owed to the tax office — calculated under the separate rules of the Tax Ordinance; this calculator doesn't cover it
This tool covers the first two — you pick them in the "Interest type" field.
Beyond interest: fixed recovery-cost compensation
In commercial transactions, on top of interest you're entitled to a fixed compensation for recovery costs — the equivalent of EUR 40, 70 or 100, depending on the value of the payment. It's due by operation of law, regardless of whether you actually incurred any collection costs. You'll find the exact thresholds and rules on biznes.gov.pl. Before you issue a debit note, it's worth verifying the counterparty and its bank account.
Current late-payment interest rates
Rates derived from the NBP reference rate of 3.75% (in force since 5 March 2026) — the same rates the calculator above applies:
| Interest type | Annual rate | How it is set |
|---|---|---|
| Statutory interest for late payment (Art. 481 of the Civil Code) | 9.25% | NBP reference rate + 5.5 pp |
| Commercial transactions — non-public debtor | 13.75% | NBP reference rate as of 1 July 2026 + 10 pp (fixed for H2 2026) |
| Commercial transactions — public healthcare entity | 11.75% | NBP reference rate as of 1 July 2026 + 8 pp (fixed for H2 2026) |
For developers and AI agents: an AI agent can compute statutory interest with the oblicz_odsetki tool on the MCP server. Endpoint map for models: llms.txt.
Frequently asked questions
What interest is a company entitled to for a late payment?
In commercial transactions: the NBP reference rate + 10 percentage points (non-public debtor) or + 8 percentage points (public healthcare entity). Statutory interest for delay under the Civil Code is the NBP rate + 5.5 percentage points.
What are the current interest rates?
As of 6 July 2026: commercial transactions — 13.75% (non-public debtor) and 11.75% (healthcare entity); statutory interest for delay (Civil Code) — 9.25%. Rates change along with the NBP reference rate.
From when to when is the interest calculated?
From the day after the payment due date to the day of payment (inclusive). Each day of delay accrues a portion of the annual rate.
How is the interest calculated in this tool?
Using the formula: amount × number of days × annual rate / 365, calculated separately for each period the given rate applied. The result is for guidance only — the binding basis depends on the contract and the law.
Commercial or statutory (Civil Code) interest — which applies to me?
If both parties are businesses (or a public entity) and the transaction concerns the supply of goods or a service, statutory interest for delay in commercial transactions applies by operation of law. You use statutory interest under the Civil Code outside commercial dealings, or where the rules on commercial transactions don't apply.
Am I entitled to anything besides interest?
In commercial transactions, yes — a fixed compensation for recovery costs of EUR 40, 70 or 100, depending on the value of the payment. It's due independently of interest and regardless of whether you incurred any real collection costs.
How do these differ from interest on tax arrears?
They're separate categories. This calculator computes interest on late civil and commercial payments. Interest on tax arrears owed to the tax office is calculated under different rules (the Tax Ordinance) and isn't covered by this tool.