2026 Comprehensive Income Tax DIY Filing Guide via Hometax

About 8 million Koreans must file comprehensive income tax (종합소득세) by May 31, 2026, and if you had any 3.3% withholding last year, that includes you. The good news — Hometax's pre-filled 간편신고 wraps it up in under 30 minutes, if you know which deductions not to miss.

Here's what's new for 2026, who must file, the exact Hometax workflow, and the mistakes that cost freelancers the most refund money.

Who actually has to file this May

Pretty much anyone who got paid outside a single W-2-style job last year. If you had only one employer and finished 연말정산 in February, you usually don't need to file again. Everyone else does.

Specifically, you're on the hook if you're a freelancer or contractor with 3.3% withholding, an N잡러 (N-job worker) mixing salary with side income, a registered sole proprietor even at zero revenue, a landlord earning over 20 million KRW in rent, or someone with financial/other income above 20 million KRW.

The 3.3% you already paid (3% income tax + 0.3% local) is a prepayment, not a final tax. May's filing reconciles it against your real liability based on actual deductions and brackets.

Tip: Log into Hometax → 신고/납부 → 종합소득세 to see whether NTS already queued a 신고 안내문 for your resident number — that tells you exactly which filing path applies.

What changed for 2026 — the expense rate rules

Two shifts matter for freelancer tax filing this year. First, the simplified expense rate (단순경비율) still applies to prior-year revenue under 24 million KRW for most service professions — tutors, designers, IT contractors, YouTubers, instructors. Below that threshold, expenses are auto-recognized at a profession-specific rate with zero paperwork.

Above 24 million KRW, you switch to the standard expense rate (기준경비율), which only auto-covers small incidentals. Major expenses must be documented with receipts and tax invoices, or they're disallowed.

Second, simplified bookkeeping (간편장부) covers most individual businesses under 75 million KRW (service) or 150 million KRW (retail/manufacturing) in prior-year revenue. Double-entry bookkeeping (복식부기) becomes mandatory above those lines, and skipping it triggers a 20% non-filing penalty on tax owed.

Tip: Check your industry code (업종코드) on Hometax before filing — it determines your expense rate percentage, and a wrong code can cost several hundred thousand won in overpaid tax.

The 30-minute Hometax 간편신고 flow

NTS's 모두채움 (pre-filled filing) is the fastest route if you're a standard 3.3% freelancer without a separate business registration. It pulls income records, withholding data, and basic deductions automatically — you just verify and submit.

Around 70% of 3.3% filers end up with a refund because the flat withholding rate overshoots actual liability for lower-bracket incomes. Refunds land in the account registered on Hometax, so confirm that's current before submitting.

Tip: If Hometax says 모두채움 isn't available for you, it usually means you had mixed income types (salary + business + rental). Use the regular 정기신고 tab and work through each income category manually.

The four deductions freelancers forget

Missing these costs real money — on a typical 40-million-KRW freelance income, they can swing your refund by 1-2 million KRW.

Here's the counterintuitive part: many N잡러s assume their salaried 연말정산 already captured family deductions, so they skip them in May. But 종소세 recalculates everything using combined income — you must re-enter dependents here too, or you forfeit the deduction against your side income portion.

Tip: 노란우산공제 is the most overlooked one — it deducts up to 6 million KRW per year for registered sole proprietors, and contributions made before May 31 still count toward the prior tax year. Enroll late if you haven't.

When to pay a 세무사 instead

Self-filing works for most 3.3% freelancers earning under roughly 50 million KRW with straightforward deductions. Hire a tax accountant (세무사) if any of these apply: mixed income over 70 million KRW (brackets shift to 24%+), first year transitioning from employee to freelancer, foreign-sourced income with tax treaty implications, real estate transactions during the year, or unfiled returns from prior years you need to clean up.

Typical fees run 100,000–300,000 KRW for individual filings, and a competent 세무사 usually recovers that through deductions you'd miss alone. For recurring freelance income above the 복식부기 threshold, ongoing bookkeeping service (월 기장료) is cheaper than year-end cleanup.

Tip: Ask any prospective 세무사 whether they're experienced with your specific industry code — construction contractors, content creators, and e-commerce sellers each have quirks that generalists miss.

Wrap-up

File by May 31, 2026 on Hometax, use 모두채움 if eligible, and verify your 업종코드, pension contributions, and dependent deductions before hitting submit. If you owe under 10 million KRW you can split payment across two installments — don't let the lump sum trigger late-filing penalties.

Next action: Log into Hometax with 공동인증서 or 간편인증 and pull up 종합소득세 → 모두채움 신고 to see what NTS already has on file. Fixing a wrong record now is far cheaper than filing an amended return (수정신고) in July.

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