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Most tax penalties come not from ignorance but from forgotten dates. This guide summarises, in plain language, the filing and payment dates businesses regularly face during 2026. If a deadline falls on a public holiday or weekend, it moves to the next business day.
Monthly returns
- Withholding and social security return: Filed and paid by the 26th of the following month. Payroll, rent and freelance withholding and social security notifications are made with this return.
- VAT return: Filed and paid by the 28th of the following month.
- Stamp duty: Declared with the withholding return for taxable documents.
- Ba-Bs forms: Filed by the end of the following month for purchases and sales above the threshold.
Provisional tax periods
Companies and sole traders keeping double-entry books file provisional tax quarterly. Filing and payment are due by the 17th of the second month after the quarter: May for Q1, August for Q2 and November for Q3. No provisional return is filed for Q4; that profit is taxed through the annual return.
Annual returns
- Annual income tax: For 2025 income, filed between 1 and 31 March 2026; paid in two equal instalments in March and July.
- Corporate tax: For the 2025 fiscal year, filed between 1 and 30 April 2026 and paid by the end of that month.
- e-Ledger certificates: Uploaded within periods that vary; your monthly bookkeeping routine must stay on track.
Three habits to never miss a deadline
- Send your documents to your accountant in the first week of every month.
- Learn the amounts due well before the deadline and add them to your cash plan.
- Check your e-Notification inbox regularly; tax office correspondence now arrives there.
Ankara Muhasebem sends clients the amounts due, with explanations, before every filing period. These dates are general rules and may change with new legislation, so confirm your own situation with your advisor.
