The Turkish tax year is a calendar year.
The annual tax return for the year has to be filed by 25 February if the income is derived exclusively from trade activities subject to the simple method of taxation and by 25 March in all other cases. No extensions are available.
Payment of tax
Income tax is withheld every month from salaries paid through a Turkish payroll under the pay-as-you-earn (PAYE) system.
The tax, when a return is filed for any outstanding liability under the aforementioned principles, is paid in two equal instalments; by the time of filing and in the fourth month thereafter. Non-residents leaving Turkey have to settle full liability within 15 days before departure.
Taxpayers filing income tax returns for their commercial or professional income must pay advance income tax (under the title of 'temporary tax'), calculated as 15% of their cumulative income as of the end of each quarter during the calendar year. This tax must be reported by the 14th day of the second month following the end of the related quarter and must be paid by the 17th day of the filing month. Tax paid in advance is credited to income tax computed on the annual tax return for the same year.