First 3 Months After Incorporating: Tax, Insurance & Corporate Account Admin Checklist

#The First Two Weeks — Your Earliest Insurance Deadlines

The day you hire your first employee starts all four insurance clocks. Employment insurance and workers' compensation insurance must both be enrolled at the Korea Workers' Compensation & Welfare Service regional office within 14 days of the first hire date. Health insurance workplace enrollment must also be filed with the National Health Insurance Service (NHIS) regional office within 14 days of the qualifying date. National pension has a slightly different deadline — workplace enrollment with the National Pension Service (NPS) must be completed by the 15th of the month following the month you first hire at least one employee.

For national pension workplace enrollment, submit the Mandatory Workplace Application form and the Workplace Subscriber Qualification Acquisition form, along with a copy of either your business registration certificate or your corporate registration certificate.

#Business Registration — Within 20 Days of Opening, Early Filing Allowed

Every business location must be registered with the district tax office within 20 days of the business start date. Early filing before the start date is also allowed, so completing business registration immediately after corporate incorporation is the most common approach. Downstream steps — issuing tax invoices and opening a corporate bank account — all require a completed business registration first.

#Health Insurance Retroactive Filing Limit — Don't Let the Window Close

Filing health insurance workplace enrollment late creates retroactive coverage restrictions. To backdate coverage more than three months before the filing date, you must submit the enrollment form along with supporting documents — such as an employment contract or certificate of employment — to the NHIS regional office. Missing the 14-day window adds administrative burden and complicates premium settlement timing.

Delayed insurance enrollment is not simply a paperwork problem — it can create gaps in employee coverage and trigger surcharge liability. The practical standard is to start preparing enrollment paperwork on the same day you hire your first employee. Retroactively settling surcharges after they accrue adds unnecessary administrative complexity right at the moment you need clean records for a grant agreement or investor due diligence.

#After the First Quarter — VAT Preliminary Filing and Early Refund Timing

For December fiscal-year corporations, January 1 through March 31 is the first-period VAT preliminary filing period. The filing deadline is April 1 through April 25, and the same framework applies to newly established businesses.

If you have grounds for an early refund — such as facility investment or exports — you can receive the refund within 15 days after the preliminary filing deadline. Standard refunds are issued within 30 days after the filing deadline. If you file for an early refund, you must deduct that amount when filing your final return. For corporations with heavy upfront capital expenditure, building the early refund timing into your cash flow plan can make a meaningful difference in liquidity management.

#By Summer — Know Your Corporate Tax Interim Payment Schedule

December fiscal-year corporations must file and pay the interim corporate tax by August 31 — within two months of the end of the interim period (January 1 through June 30). However, small and medium-sized enterprises whose interim tax calculated on the prior fiscal year's tax base is less than KRW 500,000 are exempt from filing and payment. January fiscal-year corporations have an interim period of February through July and a filing deadline of September 30. The NTS may grant automatic payment deadline extensions to qualifying small businesses affected by specific economic conditions (high exchange rates, high oil prices, etc.), so always check the official NTS tax calendar for the year you are filing.

#Working Backward From D-Day — What to Complete Before a Grant Agreement or Investor Due Diligence

When selected for a KISED (Korea Institute of Startup & Entrepreneurship Development) program such as the Early-Stage Startup Package, program funds are disbursed after the grant agreement is signed. Required documents at the agreement stage are listed in each individual program announcement, but if business registration and insurance enrollment are still incomplete, you won't be able to prepare even the basic paperwork. The 2026 Early-Stage Startup Package standard track application window ran from January 23 to February 13; the process flows: selection → agreement signing → fund disbursement.

1. Within 14 days of first hire: Complete employment, workers' comp, and health insurance enrollment (Korea Workers' Compensation & Welfare Service and NHIS regional offices)
2. Within 20 days of business start date: Complete business registration — early filing immediately after corporate incorporation is recommended
3. By the 15th of the month following the hire month: Complete national pension workplace enrollment (National Pension Service)
4. By April 25 (first-period preliminary): Complete VAT preliminary filing — assess early refund eligibility if you have capital investment
5. By August 31 (December fiscal year): Confirm interim corporate tax obligation, then file and pay if applicable

Opening a corporate bank account and obtaining a corporate digital certificate each follow different procedures depending on the bank and issuing authority. The most reliable approach is to contact your intended bank directly after completing business registration to confirm the specific documents and steps required.