How we calculate

Every Kalkoro tool follows the same three principles: the formula is explained on the page, the legal values used in the calculation are dated and sourced, and the calculation runs on your device without your inputs leaving it. This page explains what a result is based on and how it is verified.

Behind each tool is a separate engine whose only job is that calculation. Engines apply the formula from the law, regulation or textbook exactly; money calculations use decimal arithmetic to avoid floating-point errors.

Engines pass a continuously running automated test suite: boundary values, zero and negative inputs, tax bracket transitions and date edge cases such as leap years are re-verified on every change. Regulation-based engines are cross-checked against examples published by the relevant authority.

Tax brackets, ceilings, rates, coefficients and tariffs are kept apart from the code in dated records we call parameter sets. Each set has a period label and a validity range; a tool uses the set in force on the calculation date. Old periods are never deleted, so a calculation for a past date stays correct.

On every regulation-based tool page, the "Current legal parameters" box shows the values used, the date they took effect and the official source. Our sources are the consolidated laws on mevzuat.gov.tr, the Turkish Revenue Administration, the Social Security Institution, the Central Bank, ÖSYM, the Ministry of National Education, TurkStat, the Presidency of Religious Affairs and the Official Gazette.

• Rate and tariff changes published in the Official Gazette are added as a new parameter set with their effective date; the old set is closed with an end date.

• Exchange rates are taken from the Central Bank's indicative rates every business day; the rate date is shown on the page.

• Exam coefficients are the values published by the examining body for the latest exam period and are updated when a new period is announced.

• The "Last updated" date at the bottom of each tool page shows when that page's content or parameters last changed.

Results are for information only. For official matters the calculation of the relevant authority prevails, and we recommend consulting a professional before making a financial, legal or medical decision. Health tools are not a substitute for diagnosis or treatment.

Some calculations rely on simplified assumptions; those assumptions are stated in the tool's "how it works" section.

Every tool page has a "Report a bug" button; reports are stored and reviewed one by one. You can also write to info@kalkoro.com. When a verified error is fixed, a new case is added to the engine tests and the page's update date is refreshed.

The salary, amount or date values you enter are not sent to our servers; the calculation happens in your browser or in the app. Usage statistics record only which tool was used, never the input values. Details are in our privacy policy.

Content and engines are prepared by the Kalkoro team and published by Teknolojig Bilişim Teknolojileri A.Ş.. Company details and contact channels are on the About page.