Every October, the same call comes from the tax office. "You need to file this time." Or: "The notice is out, just pay it."
Same month, different instructions. Some companies file a return; others only receive a payment notice. Here is what separates the two, and what you should check before the money leaves your account.
The deadline is the 26th, not the 25th
The second-period VAT preliminary filing covers business activity from July 1 to September 30. The usual deadline is October 25, but in 2026 that date falls on a Sunday. When a deadline lands on a weekend or public holiday, it moves to the next business day, so this year the deadline is Monday, October 26.
It is only one extra day, but it gives you a weekend of breathing room. Confirm balances and transfer cut-off times on Friday and you remove the last-minute rush.
Do you file, or do you pay a notice?
The dividing line is the supply value in the previous tax period.
| Type | Who it applies to | What happens in October |
|---|---|---|
| Preliminary filing | Corporations with previous-period supply value of 150 million KRW or more | File July–September results and pay |
| Preliminary notice | Corporations under 150 million KRW, and individual general taxpayers | Pay the amount on the notice |
The notice amount is 50% of the tax you paid in the previous period. If you paid 8 million KRW for the first period, the notice comes to 4 million KRW. It is calculated mechanically, so the amount stays the same even if your sales have dropped this year.
If the notice amount is under 500,000 KRW, no notice is issued at all. In that case everything is settled in the final filing next January.
What if you got a notice but business slowed down?
This is where many owners miss an option. Even if you are in the notice group, you may choose to file a preliminary return when your results have fallen sharply.
Say you had strong sales in the first half and a steep drop in the second. Paying the notice means paying more tax now and getting it back next January — with your cash tied up in between. The same applies in reverse: if you had large input tax from equipment purchases, filing early can bring the refund forward.
The rule of thumb is simple. Check whether the last three months came in at a third or less of the previous period. If so, talk to your tax advisor about filing instead.
Three things to check before the due date
The tax itself matters less than whether the cash is in the account that day. Late October is rarely a quiet week.
First, line up everything due in the same week. Corporate card settlements, loan repayments, and payroll often cluster together. Each is manageable alone; together they drain the balance faster than expected.
Second, look at the total, not each account. With three separate bank accounts it is easy to glance at each one and assume you are fine. Payment leaves a specific account, so work out how much to move in advance.
Third, look ahead to November. Sole proprietors face interim income tax payment on November 30. If October empties the account, the pressure returns a month later.
What is left on this year's calendar
| Date | Item | Who |
|---|---|---|
| October 26 | Second-period VAT preliminary filing and payment | Corporations, individual general taxpayers |
| November 30 | Interim income tax payment | Sole proprietors |
| January 25 next year | Second-period VAT final filing | Corporations, individual general taxpayers |
Interim corporate tax payment already passed on August 31 for companies with a December fiscal year end. The final corporate tax filing comes in March, so it is worth planning that cash in the fourth quarter as well.
How Fintag helps
Fintag does not calculate your taxes. What it does help with is knowing in advance whether the money will be there on the due date.
- All accounts on one screen — see balances spread across banks as a single total.
- A forecast of your balance — an AI trained on your transaction patterns projects your future balance and how long your cash lasts.
- Upcoming payments on a calendar — card settlements, loan repayments, and maturities are collected automatically. Add tax deadlines yourself to manage them together.
- Records ready for your accountant — pick a period and accounts, and download transactions as an Excel file.
- Just ask the AI — "How much is leaving the account in the last week of October?" is answered from your connected data.
📌 Check this month's cash schedule with a single question Fintag brings your scattered accounts, cards, and loans onto one screen and projects what your balance will look like. Start with a 2-week free trial and review your October payments first. → app.fintag.kr
Thank you. The Fintag Team
Filing criteria and deadlines vary by business type and individual circumstances. Please confirm your actual filing and payment with your tax advisor.
