When is late payment interest charged?
Late payment interest is charged from the day after the tax payment deadline (Art. 53 § 4 Tax Ordinance). For PIT-38 for 2025, the payment deadline is April 30, 2026 — interest starts accruing from May 1, 2026. Interest is charged for every day of delay, including Saturdays, Sundays, and holidays.
Late payment interest rate in 2026
The late payment interest rate is set by the Minister of Finance based on the formula: 200% × NBP lombard rate + 2 percentage points, with a minimum of 8% (Art. 56 § 1 Tax Ordinance). After the interest rate cut by the Monetary Policy Council in March 2026:
- Basic rate: 10.50% annually (Finance Minister's Announcement of March 6, 2026, M.P.2026.269)
- Reduced rate: 5.25% annually (when filing correction + paying within 7 days)
- Increased rate: 15.75% annually (for arrears discovered during audit)
Interest calculation formula
Interest is calculated using the formula: Interest = (Arrears amount × Number of days × Rate) / 365. The result is rounded to full zlotys — below 50 gr is omitted, 50 gr and above is rounded up (Art. 63 § 1 Tax Ordinance). The divisor is always 365, even in a leap year.
Example: Overdue tax 5,000 PLN, 90 days late, basic rate 10.50%. Calculation: (5,000 × 90 × 0.1050) / 365 = 129.45 PLN → rounded: 129 PLN. At reduced rate (5.25%): (5,000 × 90 × 0.0525) / 365 = 64.73 PLN → 65 PLN.
When does the reduced 5.25% rate apply?
The reduced interest rate (50% of the basic rate) applies when you meet both conditions simultaneously (Art. 56a Tax Ordinance): 1) you file a legally effective correction of the declaration with justification for the correction, 2) you pay the entire tax arrears within 7 days of filing the correction. The reduced rate does not apply to arrears discovered during a tax audit.
When you don't have to pay interest
Late payment interest is not charged if its amount does not exceed three times the fee for a registered letter (Art. 54 § 1 pt 5 Tax Ordinance). In 2026, the threshold is 3 × 2.90 PLN = 8.70 PLN. If calculated interest (before rounding) does not exceed 8.70 PLN — you don't have to pay it.
How to pay interest?
You pay late interest to your individual tax micro-account (number generated at podatki.gov.pl). In the transfer title, enter: PIT, period (e.g., 2025), interest amount. You can calculate interest yourself or use the interest calculator on the Ministry of Finance website. Remember: interest is charged up to and including the day of payment.
Interest rates may change following Monetary Policy Council decisions. The rates shown apply from March 2026. Check the current rate on the Ministry of Finance website.
Frequently Asked Questions
How much is one month's interest?
At 10.50% annual rate with 5,000 PLN arrears, interest for 30 days is: (5,000 × 30 × 0.1050) / 365 = 43.15 PLN → 43 PLN. For 10,000 PLN arrears: 86 PLN per month.
Is interest charged on weekends and holidays?
Yes. Late payment interest is charged for every calendar day, including Saturdays, Sundays, and public holidays. There are no breaks in accrual.
Can I request interest forgiveness?
Yes. Under Art. 67a § 1 pt 3 of the Tax Ordinance, you can request forgiveness of tax arrears with interest in whole or in part. The tax authority may grant the request in cases justified by the taxpayer's important interest or public interest. The decision is discretionary.