Turkish Tax Late-Payment Interest Calculator
Enter the tax, the due date and the payment or assessment date. The late-payment surcharge, late-assessment interest or voluntary disclosure surcharge is worked out, with any rate changes in between.
- Tax amount50,000.00 ₺
- Period charged11 months 23 days
- Monthly rate, latest period3.7%
- As a share of the tax43.86%
- Late-payment surcharge21,928.33 ₺
- Total owed71,928.33 ₺
Late-payment surcharge rate: Cumhurbaşkanlığı (CB kararı) / GİB
Breakdown by rate period
How it is calculated
The late-payment surcharge (Law 6183 Art. 51) runs on assessed tax not paid by the due date until it is paid, with part months by the day. Late-assessment interest (Tax Procedure Law Art. 112) runs on additional or ex officio assessments from the normal due date to the assessment date, ignoring part months. The disclosure surcharge (Art. 371) is charged for every month or part month a voluntarily disclosed tax is late. The rate is set by presidential decision; the calculator uses its history.
Gecikme zammı = Vergi × Aylık oran × (Ay + Gün ÷ 30); Gecikme faizi = Vergi × Aylık oran × Tam ay; Pişmanlık zammı = Vergi × Aylık oran × Başlayan ayAll three use the monthly rate of Art. 51 of Law 6183; since 13 Nov 2025 it has been 3.7% a month. If the rate changed during the period, each part uses its own rate. Months run from the due day to the same day of the next month.Example
Tax of ₺50,000 due on 26.01.2026 and paid on 05.05.2026 is 3 months 9 days late: the surcharge is 50,000 × 3.7% × (3 + 9/30) = ₺6,105. Late-assessment interest counts 3 whole months (₺5,550) and the disclosure surcharge 4 months (₺7,400).
Frequently asked questions
What is the current rate?
3.7% a month since 13 Nov 2025. Late-assessment interest and the disclosure surcharge use the same rate.
How does the surcharge differ from the interest?
The surcharge runs on assessed but unpaid tax until it is paid. The interest runs on tax assessed later, from the normal due date to the assessment; if it is then not paid, the surcharge starts.
Is the surcharge compounded?
No. It is simple, charged separately for each month on the tax itself; earlier surcharge is not surcharged again.
What if the due date falls on a weekend?
The deadline moves to the end of the next working day (Art. 18). Enter that working day as the due date.