Korean Freelancer & Solo Developer Tax Guide

The Expat's Korean Freelancer & Solo Developer Tax Guide: From Hometax to Year-End Filing

Let me tell you about a painful 3,000,000 KRW mistake I made during my first year running Graxel.ai. I was so focused on shipping code that I completely ignored my expense tracking. When May rolled around, the tax office assumed my software business had a 90% profit margin because I hadn't properly registered my AWS and API expenses. I paid the price—literally. For expats and international freelancers operating in Korea, the tax system can feel like a labyrinth of digital certificates and confusing acronyms. Here is the developer's guide to surviving it.

Business Registration: Simplified vs. General Taxpayer

When you get your business license (사업자등록증), you must choose your tax status. A Simplified Taxpayer (간이과세자) charges no VAT or low VAT and has minimal reporting, which sounds great. But if you are a solo developer doing B2B work—invoicing other Korean companies—you almost always need to register as a General Taxpayer (일반과세자). Korean companies need you to issue proper electronic tax invoices (세금계산서) to claim their own expenses, and simplified taxpayers often can't do this effectively. The Ministry of SMEs and Startups provides resources on this, but standardizing as a General Taxpayer is usually the safer bet for tech workers.

The VAT Grind (January & July)

Value Added Tax (부가세) filing happens twice a year: January and July. The absolute most critical step you must take today is logging into Hometax and registering your business credit card. If you buy a new MacBook or pay for server hosting with an unregistered card, claiming that 10% VAT back becomes a manual, receipt-hunting nightmare. Register the card, and Hometax automatically categorizes your business expenses.

Comprehensive Income Tax (The May Monster)

Every May, freelancers and solo devs must file their Comprehensive Income Tax (종합소득세). The tax office calculates your liability based on Revenue minus Expenses. If your revenue is low, you can use the government's "Standard Expense Ratio" (단순경비율). But once you cross a certain threshold (usually 24M KRW for freelancers, though check current tables via KOSIS statistics), you must use bookkeeping (기장). If you don't track expenses, your taxable income skyrockets.

Top 5 Expenses Solo Devs & Expats Forget to Claim

• Cloud Infrastructure (AWS/GCP/Vercel): Because these are foreign companies, they often don't issue Korean tax invoices. You must manually submit your receipts to prove these are business expenses.
• SaaS & APIs: OpenAI, GitHub Copilot, Figma. These add up. Track them meticulously.
• Hardware Depreciation: That 4M KRW laptop isn't expensed all at once; it depreciates over a few years.
• Telecom & Internet: If you use your SKT/KT phone for business, a portion of that bill is a deductible expense.
• Home Office Rent: If your registered business address is your apartment, a percentage of your rent and utilities can legally be claimed as a business expense.

The National Health Insurance Shock (November)

Here is the trap that catches every new expat freelancer. In May, you report a successful year of income. Six months later, in November, the National Health Insurance Service (NHIS) receives your updated income data and retroactively adjusts your monthly premiums. I've seen freelancers have their monthly premiums jump by 300,000 KRW overnight. You must budget for this "November Shock." Joining the Yellow Umbrella Fund can help lower your taxable income base, indirectly buffering this blow.

When to Hire a Tax Accountant (CPA/세무사)

If you are making under 30M KRW, you can probably brute-force Hometax using translation tools and our blog updates. But once your revenue crosses 50M KRW—or if you are dealing with foreign currency payouts from global App Stores—hire a Korean tax accountant. They charge around 100,000 to 150,000 KRW a month for bookkeeping (기장대리), and they will save you thousands of dollars in missed deductions and audit penalties. Consider it the best SaaS subscription you'll ever buy.