Income Tax Filing Guide: Tax-Saving Strategies for Freelancers and Business Owners

Comprehensive income tax (종합소득세) is Korea's primary tax on individual income from sources such as business, freelance work, rental properties, and investments. Unlike salaried employees whose taxes are handled through year-end settlement, freelancers and business owners must file their own returns. Understanding the tax brackets and available deductions can significantly reduce your tax burden.

Who Must File?

You must file a comprehensive income tax return if you have:

• Business income (사업소득) — self-employed, freelance, or side business earnings
• Rental income (임대소득) — income from renting out property
• Multiple sources of income — salary plus freelance work, for example
• Freelance income subject to 3.3% withholding — you likely overpaid and may get a refund
• Financial income exceeding 20 million won annually (interest + dividends)

2026 Tax Brackets

Korea uses a progressive tax system with 8 brackets:

• Up to ₩14M: 6%
• ₩14M - ₩50M: 15% (cumulative tax: ₩840K + excess × 15%)
• ₩50M - ₩88M: 24% (cumulative: ₩6.24M + excess × 24%)
• ₩88M - ₩150M: 35% (cumulative: ₩15.36M + excess × 35%)
• ₩150M - ₩300M: 38% (cumulative: ₩37.06M + excess × 38%)
• ₩300M - ₩500M: 40% (cumulative: ₩94.06M + excess × 40%)
• ₩500M - ₩1B: 42% (cumulative: ₩174.06M + excess × 42%)
• Over ₩1B: 45% (cumulative: ₩384.06M + excess × 45%)

Plus local income tax (지방소득세) at 10% of the calculated tax amount.

Key Deductions to Maximize

• Basic deduction (기본공제): ₩1.5M per person for yourself, spouse, and dependents
• National pension contributions (국민연금): Fully deductible
• Health insurance premiums: Fully deductible
• Housing-related deductions: Mortgage interest, monthly rent payments (for qualifying renters)
• Charitable donations: Tax credit of 15-30% depending on amount
• Education expenses: Up to ₩3M per child for tuition
• Medical expenses: Amounts exceeding 3% of total income

Freelancer-Specific Strategies

Freelancers in Korea face unique tax considerations. The 3.3% withholding (소득세 3% + 지방소득세 0.3%) deducted from each payment is just an advance payment. Your actual tax liability is determined when you file. If your deductions are high, you may receive a significant refund.

• Keep ALL business receipts — equipment, software, transportation, meals during client meetings
• Consider simplified bookkeeping (간편장부) if your revenue is below the threshold
• Deduct home office expenses if you work from home (proportional to work space)
• Estimated tax payments (중간예납) in November help avoid a large April bill

Filing Deadlines

The comprehensive income tax filing period is May 1-31 every year. You report income earned in the previous calendar year. Late filing incurs penalties: 20% of unpaid tax as a penalty, plus 0.025% per day in late payment interest. If you're a first-time filer or had a significant change in income, start preparing your documents in March.

Note: This calculator (종합소득세 계산기) is different from our Freelancer Tax Calculator. The Freelancer Tax Calculator focuses specifically on 3.3% withholding tax analysis for freelance income, while the Income Tax Calculator provides a comprehensive calculation across all income types with detailed deduction options.