Who pays?
The debtor pays late payment interest on tax, social security premiums or other public receivables not paid on time. For tax, the taxpayer or the person liable (e.g. an employer withholding tax); for SGK, the employer.
How it is calculated
Under Law No. 6183 art. 51, 3.7% per month from the due date (since 13.11.2025); fractions of a month are counted by days (monthly rate ÷ 30 × days).
Formula: interest = debt × 3.7% × full months + debt × 3.7% ÷ 30 × remaining days.
Example
TRY 25,000 withholding tax due 26 August 2026, paid on 21 October 2026:
- 26.08 → 26.09: 1 full month; 26.09 → 21.10: 25 days
- 25,000 × 3.7% = TRY 925 (1 month) + 925 ÷ 30 × 25 = TRY 770.83
- Late payment interest ≈ TRY 1,695.83
Late payment interest, delay interest and voluntary disclosure surcharge
| Concept | When? | Rate |
|---|---|---|
| Late payment interest (Law 6183 art. 51) | Assessed debt paid after the due date | 3.7% a month |
| Delay interest (Tax Procedure Law art. 112) | Tax assessed later (audit, additional assessment) | Same as late payment interest |
| Voluntary disclosure surcharge (art. 371) | Tax declared late on the taxpayer's own initiative | Same as late payment interest |
If the rate changes during the period, each period uses its own rate; this tool uses one rate. For long-standing debts, rely on the tax office or SGK calculation. Comparison of penalty options: Tax loss penalty.
Legal basis
Law No. 6183 art. 51; Tax Procedure Law No. 213 arts. 112 and 371; Law No. 5510 art. 89.