Comprehensive income tax filing generally requires an income statement, withholding receipts, expense documentation (for business income), proof of dependents (family relationship certificates, etc.), and foreign tax payment certificates if claiming the foreign tax credit. Most of this is auto-populated on Hometax e-filing, but foreign documents must be attached manually.
Failing to file at all triggers a non-filing penalty (20% ordinary, 40% for fraud). Filing but under-reporting the tax due triggers an under-reporting penalty (10% ordinary, 40% for fraud). On top of either, a late-payment penalty of 0.022% per day (roughly 8% annually) accrues for the unpaid period.
Basic filing document checklist
A late filing is still better than no filing
Even after missing the May deadline, voluntarily filing a "late filing" can reduce the non-filing penalty by up to 50% (the reduction shrinks the longer you wait). Filing on your own before the tax office contacts you is always the better move.
Frequently Asked Questions
Related Topics
Who Must File a Global Income Tax Return, How, and By When
Whether you need to file, how to do it on Hometax, and the May filing deadline (with its exceptions).
Income Tax Refunds and the Current Rate Table
Korea's 8-bracket progressive income tax table for 2026, and how to check and receive your refund.