In English
Koray Öner
Koray Öner (also written Koray Oner) is a freelance software developer in Türkiye. He builds free, open-source calculators for Turkish payroll, income tax, social security (SGK) and pensions, and writes the articles that explain the rules behind them. This site, korayoner.dev, is where they live. The site itself is in Turkish; this page is a short overview in English.
Türkçe: Hakkımda · Çalışma dizini
- Calculators
- 61
- Articles
- 63
- Papers with a DOI
- 8
- Automated checks
- 221
What the site does
Turkish payroll, tax and pension rules change at least once a year: the minimum wage, the income tax brackets and the social security ceiling each January, pensions every January and July. The calculators on this site apply the rules of each year, so a salary, a severance payment or a pension can be computed for the year it belongs to, not only for today.
- The calculators run in your browser. The amounts you enter are not sent to a server, and there is no sign-up and no advertising.
- Every legal parameter (brackets, ceilings, exemptions, rates) is read from a single source file and checked against the official text.
- Articles answer one question with the site's own calculation, and state their assumptions in the text.
How the numbers are checked
Sources are primary: the Official Gazette (Resmî Gazete), the Revenue Administration (GİB), the Social Security Institution (SGK), TurkStat (TÜİK) and the Central Bank (TCMB). Every number in an article that contains a calculation is reproduced by an automated test from the site's own calculation engines; 221 checks run on every change. Claims that depend on a date carry an expiry date, and the build fails when it passes. Corrections are logged on the publishing principles page (in Turkish).
AI agents help write code, drafts and charts. They are not a source of facts: the figures are recomputed by tests, and the responsibility is Koray Öner's.
Where to start
Selected calculators. The pages are in Turkish; the numbers speak for themselves.
- Gross-to-net salaryMonthly payroll for every month of the year, with income tax brackets, the SGK ceiling and the minimum-wage exemption; payroll years 2020–2026.
- Payslip auditEnter your payslip lines and see which deduction differs from the expected amount, and why.
- Severance and notice paySeverance (kıdem) and notice (ihbar) pay with the current statutory ceiling.
- Retirement pensionHow contribution days and earnings turn into a monthly pension under the SSK and Bağ-Kur rules.
- Retirement dateEarliest retirement date from your first insurance date, age and contribution days.
- Tax bracket creepHow much extra income tax your wage pays because the brackets rose less than wages.
- Annual income tax returnIncome tax on rent, freelance and multiple-employer income, with the declaration thresholds.
- Employer costWhat a gross or net salary costs the employer, including SGK and unemployment insurance shares.
Research with a DOI
Papers deposited on Zenodo with a permanent DOI, all linked to ORCID 0009-0005-8730-3577. The papers are written in Turkish; titles are given as published.
Open source
The calculation core for payroll, severance, pensions, rental income, taxes and loans is published on npm as hesap-cekirdegi under the MIT licence. It has no dependencies, runs the same in the browser and in Node.js, and is the code the calculators on this site use. Source: GitHub · npm.