Late payment surcharge calculator (gecikme zammı)
Estimate the surcharge on a tax paid late, using the 4.5% and 3.7% monthly rates for the periods they apply to.
Estimate the late payment surcharge (gecikme zammı) on an overdue tax amount. The monthly rate is set by Presidential Decision and applies to the period it covers. Part months are calculated by days. Nothing you enter is stored.
Rates applied
| Period | Monthly rate | Basis |
|---|---|---|
| 21 May 2024 to 12 November 2025 | 4.5% | Presidential Decision effective 21.05.2024 |
| From 13 November 2025 | 3.7% | Presidential Decision No. 10556, Official Gazette 13.11.2025 |
The same 3.7% monthly rate is used for late payment interest (gecikme faizi) and the voluntary disclosure surcharge (pişmanlık zammı) under the Tax Procedure Law. For due dates before 21 May 2024, earlier rates apply and are not covered here.
How it is calculated
The surcharge is simple interest: for each day of delay, the monthly rate in force on that day divided by 30. The tool is an estimate for planning. The tax office's own calculation, including any day-count conventions and rounding, is what you pay.
Sources: KPMG Türkiye tax bulletin on Presidential Decision No. 10556; Law No. 6183, art. 51. Last checked 4 November 2026.
For information only; not tax, legal or investment advice. Rules change, so check the official source before acting.