January 8, 2026

• Submission and payment of the declaration of payments made by notaries against receipts for the December 2025 period

January 12, 2026

• Uploading electronic ledger certificates for September 2025 for income taxpayers who opted for monthly uploads
• Declaration and payment of special consumption tax on petroleum and natural gas products for the December 16-31, 2025 period

January 14, 2026

• Uploading electronic ledger certificates for September 2025 for other taxpayers who opted for monthly uploads

January 15, 2026

• Declaration and payment of local minimum top-up corporate tax for 2024 (VUK Circular/193)
• Declaration and payment of special consumption tax on alcoholic beverages, non-alcoholic beverages, tobacco products and makarons for the December 2025 period
• Declaration and payment of special consumption tax on durable goods and other goods for the December 2025 period
• Declaration and payment of special consumption tax on motor vehicles not subject to registration for the December 2025 period
• Declaration and payment of special communication tax for the December 2025 period
• Declaration and payment of banking and insurance transactions tax for the December 2025 period
• Notification and payment of the resource utilization support fund deduction for the December 2025 period
• Submission and payment of the trade registry fees notification for the December 2025 period

January 20, 2026

• Declaration and payment of advertisement tax for the December 2025 period
• Declaration and payment of entertainment tax on mutual betting for the December 2025 period and payment of other entertainment taxes
• Declaration and payment of electricity and gas consumption tax for the December 2025 period
• Declaration and payment of fire insurance tax for the December 2025 period
• Declaration and payment of games of chance tax for the December 2025 period
• Declaration and payment of inheritance and transfer tax related to games of chance defined under Law No. 5602 for the December 2025 period

January 26, 2026

• Declaration and payment of special consumption tax on petroleum and natural gas products for the January 1-15, 2026 period
• Declaration and payment of withholdings made under Income Tax Law and Corporate Tax Law Articles 15 and 30 through the withholding and premium service return for the December 2025 period
• Declaration and payment of withholdings for the October-November-December 2025 period through the withholding and premium service return for taxpayers entitled to quarterly filing
• Declaration and payment of withholdings made under the provisional article of the Income Tax Law for the October-November-December 2025 period
• Declaration and payment of stamp tax withheld from payments and stamp tax payable against receipt by taxpayers with continuous liability for the December 2025 period
• Declaration and payment of accommodation tax for the December 2025 period
• Declaration and payment of value added tax withheld by responsible parties for the December 2025 period

January 28, 2026

• Declaration and payment of value added tax for the December 2025 period
• Declaration and payment of value added tax for the October-November-December 2025 period