2026 Turkish Tax Calendar and Key Deadlines for Foreign-Owned Operations

A foreign-owned Turkish subsidiary lives by a tax calendar that is denser than what most parent companies expect. Filings happen monthly, quarterly and annually, and missing a deadline triggers automatic penalties, not warning letters. This guide walks through the 2026 calendar from a foreign management perspective: what your Türkiye-based finance team must do each month, when, and why it matters at the group level.

Why this calendar matters more than you think

Turkish tax authorities (Gelir İdaresi Başkanlığı / GIB and the Social Security Institution / SGK) operate on tight schedules. Unlike some jurisdictions where late filings get a grace period, Türkiye applies penalties automatically and in many cases immediately. A missed VAT filing in March can become a five-figure problem by June with accumulated interest. The trick is not heroic catch-up but a calm monthly rhythm.

Monthly recurring obligations

These happen every month and dominate the calendar:

By the 28th of each month: VAT (KDV) return for the preceding month. This is the primary indirect tax filing. If you sold goods or services in May, you file the May VAT return by 28 June.

By the 26th of each month: Withholding tax (Muhtasar) and SSI premiums combined. Türkiye merged these in 2020 into a single declaration called "Muhtasar ve Prim Hizmet Beyannamesi". Your finance team files what you withheld from employee wages plus what you owe to social security. One filing, two obligations.

By the 26th of each month: Income tax withholding on supplier services. If your company paid a Turkish freelancer or service provider, you may have withheld income tax at source. This is reported separately.

Within the same month: e-Invoice and e-Ledger compliance. Companies above the e-Invoice threshold (~3 million TRY annual revenue, 2026 limit) must issue all invoices electronically. e-Ledger files and their certificates (berat) are uploaded to GİB on a fixed schedule: corporate taxpayers that upload monthly do so by the 14th of the fourth month after the ledger month (May 2026 by 14 September 2026, for example).

Quarterly obligations

By the 17th of the second month following the quarter: Provisional corporate tax. Türkiye uses a system of "geçici vergi" (provisional tax). Your company pays estimated corporate tax based on year-to-date profits, every quarter. The May 2026 deadline covers Q1 2026 (January-March). Since Law No. 7566 the fourth quarter is filed as well (by 17 February). The pre-payment is offset against your annual corporate tax bill in April 2027.

If your Q1 was unusually profitable due to a one-time event, your provisional tax bill will be high. Plan cash flow around this rhythm.

Annual obligations

Annual corporate tax return: 1-30 April 2027 for fiscal year 2026. This is the consolidated annual filing where the provisional payments are reconciled. The tax is paid within the same period, by 30 April.

Income tax return (for sole proprietors and partners, not for limited/A.Ş. companies): March 2027. Most foreign subsidiaries are A.Ş. (Anonim Şirket) or Ltd. Şti., so this is less relevant. Still worth knowing if your local partner is structured differently.

Annual SSI / pension reconciliation: varies by employee status.

Sector-specific 2026 additions

Several reporting obligations affect foreign-owned operations specifically:

KDV2 (VAT withholding): applies to many sectors served by foreign-owned buyers. If your Turkish subsidiary buys services from local subcontractors in construction, cleaning, consulting, or fabrication, you may be required to withhold and remit a portion of the VAT yourself. Monthly filing and payment by the 25th.

CBAM data collection for exporters. If your Turkish subsidiary exports goods to the EU (cement, iron, steel, aluminium, fertilisers, hydrogen, electricity), your EU buyers need embedded-emissions data for each calendar year: since 1 January 2026 the EU importer files an annual CBAM declaration, the first one by 30 September 2027 for 2026 imports, and many buyers ask for interim figures during the year. This is not a tax filing but a reporting obligation your finance team will face questions about.

Beneficial ownership (UBO) notification. Corporate taxpayers file the beneficial-owner form as an annex to each provisional tax return and to the annual corporate tax return. The end-of-August date applies only to filers that are not corporate taxpayers.

Practical advice for the parent company

Three observations from running Turkish subsidiaries for foreign-headquartered groups:

1. Trust your CPA (Mali Müşavir), but verify the calendar.

Most Turkish CPAs are competent but operate in Turkish and respond to local cultural cues. Ask for a written monthly checklist with deadlines (you'll often have to request this, as it isn't volunteered). Confirm in writing each month that filings are completed.

2. Build a parallel calendar at the parent company.

Don't rely solely on your Turkish team. Have a simple shared calendar in whatever tool your group already uses, where each filing has a deadline and an owner. Parent CFO gets a notification three days before each deadline. This catches problems before they become penalties.

3. Know the cost of delay.

Late payment of VAT, withholding or corporate tax accrues a late-payment surcharge (gecikme zammı) under Article 51 of Law No. 6183, set at 3.7% per month since 13 November 2025. A late or missing return triggers separate penalties under the Tax Procedure Law, and late SSI premiums accrue their own charges. On a 100,000 TRY VAT bill, one month of delay costs 3,700 TRY in surcharge alone, before any penalty.

How Birasyo helps

Birasyo ERP is built for Turkish tax compliance. Monthly VAT, withholding and SSI returns are prepared automatically with the right format for your CPA to upload to GIB. e-Invoice and e-Ledger compliance is integrated. The system flags upcoming deadlines and tracks completion, so your parent company can see at any moment that the Turkish subsidiary is on schedule.

Explore Birasyo for foreign-owned operations

Keeping to the calendar

The Turkish tax calendar is dense but predictable. Subsidiaries that treat each filing as a separate event struggle, while those that run it as a steady monthly rhythm, supported by ERP that prepares filings automatically and gives the parent company visibility, rarely do. The costly part of compliance is often the chaos of forgetting, not the tax itself.