This legal interest calculator is provided by Hesapstan for estimating simple interest in Turkey using legal interest, GIB tax deferment interest, TTK 1530 late-payment interest, or a custom annual rate.
What does this legal interest calculator do?
This calculator estimates simple interest from a principal amount, a start date and an end date. It supports four modes: statutory legal interest, GIB tax deferment interest, TTK 1530 late-payment interest and a user-entered annual rate.
- In statutory legal interest mode, it automatically splits periods before and after 1 June 2024.
- In tax deferment mode, it pre-fills the GIB deferment interest rate and allows the user to edit it.
- In TTK 1530 mode, it estimates commercial late-payment interest for the supply of goods and services.
- In custom mode, it applies the annual rate entered by the user.
This calculation is for information only. The correct interest type, start date and rate may depend on the contract, the type of receivable, a court decision or current official rules.
Legal interest, statutory interest and other rates
In everyday language, legal interest often refers to statutory interest, but not every legal-looking interest calculation uses the same rate. This calculator separates statutory interest, tax deferment interest, TTK 1530 late-payment interest and custom-rate calculations.
Statutory interest is the general legal rate used when no special rate or special rule applies. Tax deferment interest belongs to Turkish tax debt deferment or instalment cases. TTK 1530 late-payment interest applies to certain commercial supply transactions.
The amount and dates alone do not determine the correct rate. The legal nature of the debt, the parties, the contract and any court decision may change the applicable interest type.
How is statutory legal interest calculated?
Statutory legal interest is calculated as simple interest by multiplying the principal by the annual rate and the number of days, then dividing by 365. In this calculator, statutory interest mode also reflects the rate change effective from 1 June 2024.
Simple interest = principal × annual rate × number of days / 365. For example, for 80,000 TL, 120 days and a 24% annual rate, the calculation is 80,000 × 0.24 × 120 / 365.
If the selected period crosses 1 June 2024, the calculator splits the period into two parts: days before the change are calculated at the old rate, and days after the change are calculated at the new rate.
Why does 1 June 2024 matter?
Turkey's statutory legal interest rate started to apply as 24% annually from 1 June 2024. Before that date, the general statutory rate was 9%. A date range that crosses this threshold should not be calculated with a single rate.
For example, if a receivable starts in May 2024 and ends in July 2024, the days before 1 June 2024 are calculated at 9%, while the days from 1 June onward are calculated at 24%.
The automatic period split applies to statutory legal interest mode. Tax deferment and TTK 1530 modes use the rate shown or entered in the form and do not automatically split historical rate changes.
When should GIB tax deferment interest be used?
GIB tax deferment interest is not a general lawsuit or receivable interest rate. It relates to deferred or instalment-based treatment of Turkish public tax debts.
The calculator pre-fills the GIB deferment interest rate, but the field remains editable because these rates can change over time. For older periods or specific tax procedures, the applicable rate should be checked from official sources.
Tax deferment rates have changed historically. This calculator does not split tax deferment interest automatically by historical rate periods, so the user must verify the correct rate for the relevant period.
What is TTK 1530 late-payment interest?
TTK 1530 late-payment interest is intended for late payment in commercial supply of goods and services. It should not be used as a general default interest rate for consumer debts, personal debts or every type of legal claim.
In this mode, the calculator uses the current TTK 1530 rate published by the Central Bank of the Republic of Turkey and can optionally add the minimum collection compensation amount if the user selects it.
TTK 1530 mode should be considered only for qualifying commercial supply transactions. The parties and the nature of the contract should be checked before using it as the applicable interest rate.
What is the custom rate mode for?
Custom rate mode is useful when a contract, court decision or other document specifies a different annual interest rate. The calculation method stays the same, but the annual rate is entered by the user.
For example, if a contract states a 30% annual rate, the user can enter the principal, date range and 30% to estimate simple interest. The calculator still does not apply compound interest.
Entering a custom rate does not mean that the rate is legally valid or enforceable. The contract, law and any court decision must be assessed separately.
How is the day count handled?
The calculator counts days by including the start date and excluding the end date. This is a practical approach for date-range interest calculations.
For example, a period from 1 March to 11 March is calculated as 10 days. If the end date is a payment date or settlement date, check whether that day should be included for your specific formal calculation.
In a legal or official context, interest may start from a notice date, default date, lawsuit date, judgment date or another legally relevant date.
Simple interest versus compound interest
This calculator uses simple interest. In simple interest, the interest is calculated only on the principal; interest from previous periods is not added back to the principal.
Compound interest adds interest to the base amount at intervals and then calculates future interest on the new total. This calculator does not cover compounding, capitalization or bank-style interest schedules.
For many practical legal estimates, users first need principal, days and an annual rate. This calculator focuses on that basic simple-interest estimate.
Example calculation
Assume a 120,000 TL receivable with a start date of 15 April 2024 and an end date of 15 July 2024. In statutory interest mode, the calculator splits the period into days before 1 June 2024 at 9% and days from 1 June 2024 onward at 24%.
The useful part of this example is the period breakdown, not only the final total. It shows why a single-rate quick calculation may differ from the calculator result.
Examples show the calculation logic. The actual start date, interest type and applicable rate must be checked for the specific case.
Limitations of this calculator
This calculator provides a practical simple-interest estimate; it does not determine the final official interest for every legal claim. In particular, tax deferment and TTK 1530 modes do not automatically split the calculation across historical rate changes.
- It does not calculate compound interest.
- It does not calculate foreign-currency claims, exchange differences or inflation adjustment.
- It does not decide the legally correct interest start date.
- It does not add court fees, enforcement costs or attorney fees.
- It does not automatically split all historical rate changes for tax deferment or TTK 1530.
Before using the result in litigation, enforcement, tax filings, accounting records or formal demands, verify current official rules and obtain professional advice where needed.
Related calculations
Legal interest is often only one part of the financial picture. A legal dispute or enforcement process may also involve court fees, expense advances, enforcement costs or attorney fees.
For that reason, the interest result should not be treated as the full cost of a lawsuit or enforcement file. It estimates the time-based increase of a receivable only.
Frequently Asked Questions
How is legal interest calculated in Turkey?
The principal is multiplied by the annual rate and the number of days, then divided by 365. This calculator uses simple interest.
Why does the statutory rate change in 2024?
The statutory legal interest rate applies as 24% annually from 1 June 2024. Before that date, the general statutory rate was 9%.
Can GIB tax deferment interest be used for any debt?
No. It relates to Turkish tax debt deferment or instalment procedures and should not be used automatically for general legal receivables.
Is TTK 1530 late-payment interest for consumer debts?
Generally no. TTK 1530 is intended for late payment in commercial supply of goods and services.
Can this result be used as an official court calculation?
No. It is informational. The correct rate, start date and legal basis should be checked before formal use.