Korea Income Tax Interim Prepayment 2026: Got a November Notice? Pay by November 30

Comprehensive income tax interim prepayment (종합소득세 중간예납) is how people with business or other comprehensive income in Korea pay part of this year’s income tax in advance. The NTS calculates half of last year’s income tax, sends notices between November 1 and 15, and the payment deadline is November 30, 2026 (NTS tax calendar). If you started reporting side-business income, here is how to read the notice.

General information only — not professional advice. Check with the NTS (☎126) or a tax professional.

Who has to make an interim prepayment?

• Residents with comprehensive income, mainly business income (Income Tax Act Art. 65)
• Excluded: people with only income types set by decree (e.g., wage income only) and people who started a business this year

How is the amount calculated?

• Interim tax = base amount (last year’s income tax) × 1/2, rounding down below KRW 1,000
• If the amount is under KRW 500,000, no notice is issued (Hometax guidance).

How do I pay the interim prepayment? (step by step)

1. Check the notice (mail or e-notice) for the amount and the Nov 30 deadline.
2. Log in to Hometax or Sontax and look up the notice under Payment/Notice/Refund.
3. Choose a method: Hometax bank transfer, credit card, Internet Giro, or a bank.
4. Pay by November 30; late payment can incur penalty tax.

What if my first-half income dropped sharply?

If tax computed on Jan–Jun 2026 income (the interim estimate) is below 30% of the base amount, you may file and pay the estimate instead between Nov 1 and 30.

• If the estimate is under KRW 500,000, you pay nothing but must file the estimate return to cancel the notice.
• Double-entry bookkeepers with no base amount but first-half business income must file an estimate.
• Amounts over KRW 10 million can be paid in installments.

FAQ

Q. Will I get a notice for small side income?
A. Not if half of last year’s tax is under KRW 500,000.

Q. Is the prepayment lost money?
A. No. It is credited against your May final return; overpayment is refunded.

Q. Where do I file an estimate?
A. In Hometax’s tax filing menu (interim estimate return). Menu names can change; confirm on Hometax.

Q. What if the deadline is a weekend?
A. It moves to the next business day. Nov 30, 2026 is a Monday.

Read next

• Side hustle taxes basics
• Small business support
• Earned income tax credit late application

📘 $4.99 PDF guide – interim prepayment & income tax calendar: https://kzk.kr/go/guide

Not professional advice. Information as of Oct 27, 2026.