How is a month fraction handled?

For late surcharge the fraction is calculated daily (monthly rate/30). For late interest month fractions are ignored. For voluntary-disclosure surcharge, every month and any part of a month counts as one full monthly period.

What happens if the rate changes mid-period?

For late surcharge the full-month segment keeps the old rate; on the daily fraction the new rate applies from the effective day (per Tahsilat General Circular examples). The tool segments per the dated GİB rate schedule.

Is the result an official assessment?

No. This is a preliminary estimator. The official amount may differ based on administration records and current legislation.

Is deferment interest calculated?

No. Deferment/instalment interest (6183 Art.48) is a separate product and is out of scope for this tool.

Does the tool verify voluntary-disclosure eligibility?

No. The voluntary-disclosure surcharge amount is estimated; the tool does not decide whether VUK 371 conditions are met.

Turkey Tax Late Interest and Surcharge Calculator 2026

Turkey 2026 current monthly rate is 3.7% (from 13.11.2025, CK 10556). Late-payment surcharge (6183 Art.51), interest on additional assessment (VUK 112) and voluntary-disclosure surcharge (VUK 371) each follow their own rules on the dated GİB rate schedule. Preliminary estimate only; deferment interest is out of scope.

Calculation Parameters

Select one scenario: late-payment surcharge (6183 Art.51), interest on additional assessment (VUK 112) or voluntary-disclosure surcharge (VUK 371). Rates are segmented per the dated GİB schedule. Not supported: deferment/instalment interest, restructuring, force majeure, litigation-settlement periods, or combined assessment interest with a later post-due surcharge.

Current 2026 monthly rate (info): interest %3.70 • surcharge %3.70. The calculation uses the effective-date rate segments falling within the period.

No live upstream; the embedded GİB rate schedule is being used. Official source (GİB)

Mid-period rate changes are segmented per the GİB schedule. If the rate changes within a full month, the whole month keeps the old rate; within a month fraction the new rate applies from the effective day. Daily rate = (monthly/100/30) rounded up to 6 decimals (RG 04.03.2005 / GİB examples). Earliest supported date: 02.01.2004.

Tax Principal Amount (₺)

Unpaid tax principal amount.

Calculation Scenario

One legal scenario is calculated for a given date range. Assessment interest and the later payment-delay surcharge are not automatically combined.

Declaration Type

Current monthly rate (info only)

The calculation does not use a manually entered rate; the dated GİB schedule is used. This field only displays the current rate.

Approximate daily rate: 0.1233

Due Date

Enter the valid/official due date you know (legal final payment date for surcharge; normal due date for late interest; normal due-date start for remorse). The tool does not auto-shift this date. Earliest supported date: 02.01.2004; earlier periods are not calculated.

There is no automatic Saturday/Sunday or public-holiday shift. If a holiday or special rule extended the deadline, enter that extended valid due date yourself; this tool does not verify all official holidays or debt-type-specific extensions.

Payment Date

For late surcharge: the actual/planned payment date; for late interest: the end of the assessment/notification period; for voluntary disclosure: the last day of the 15-day payment window (estimated).

Add Tax-Loss Penalty

Calculation Result

This scenario calculates only the late surcharge (or voluntary-disclosure surcharge); deferment interest is not included.

Applied rule: late surcharge is computed on full months + remaining days/30 (Law No. 6183 Art. 51).

Delay Days0

Principal AmountTRY 100,000.00

Late Surcharge Amount - Applied Rate (%)%0.00

Late Surcharge AmountTRY 0.00

6183 Art.51: full months + remaining days/30. On a rate change the full month keeps the old rate; on the daily fraction the new rate applies from the effective day. The applied segments are listed below.

Tax-Loss PenaltyTRY 0.00

Total PayableTRY 100,000.00

Verify on the official GİB calculator screen

Preliminary estimate only; this is not an official assessment, notice or tax-office debt. Use the GİB / tax-office record for the binding amount.

Frequently Asked Questions

No. Late interest (VUK 112) applies to complete months before assessment; late surcharge (6183 Art.51) applies after the payment due date of a finalised public receivable. They are not automatically combined over the same date range.

Official references

Use the primary sources below for the rate schedule, month/day rules and any binding amount. The tool also relies on the CK 10556 GİB note, the RG 04.03.2005 Collection General Circular and the GİB voluntary-disclosure guide.

Sources were reviewed on 13 September 2026. The engine segments per the GİB rate schedule; deferment interest and restructuring are out of scope.

Legal Disclaimer

Calculation tools are for informational and preliminary calculation purposes only. Legislative changes may not be reflected immediately in the calculation tools available on the site. They are not binding in official declarations or legal proceedings. They do not replace financial consultancy or legal advice. For definitive results, you can contact me. ozcankutlu.com cannot be held responsible for damages arising from calculation errors or legislative changes.