2026 Income Tax Return (Kakutei Shinkoku) — Filing and Payment Deadline

Income tax returns and payments for 2026 are due by Monday 15 March 2027 (the standard 15 March deadline falls on a weekday this year, so there is no extension). Late filing adds penalties and interest; refunds can be claimed for up to five years. Consumption-tax returns for sole proprietors are due 31 March.