The moment you register a business in Korea, value-added tax (VAT) filing becomes a recurring obligation you cannot avoid. "Is this a preliminary filing or a final filing this time?", "Do simplified taxpayers really only file once a year?", "How much do I actually lose if I miss the deadline by a single day?" Business owners ask themselves the same questions every time a filing deadline approaches, often bouncing between the Hometax portal and a search engine to double-check. New business owners, and anyone who recently switched from simplified to general taxpayer status, are especially prone to confusing preliminary filings, final filings, and preliminary tax notices, sometimes missing a deadline entirely as a result.
VAT filing frequency and method differ substantially between corporations, individual general taxpayers, and simplified taxpayers, and because a deadline that falls on a Saturday, Sunday, or public holiday automatically rolls forward to the next business day, the exact date needs to be reconfirmed every year. This guide lays out Korea's 2026 VAT filing and payment deadlines by taxpayer type, explains exactly how much penalty tax accrues if you miss one, and shows how to estimate your expected payment in advance.
1. Why VAT Filing Feels So Confusing
VAT is an indirect tax borne by the end consumer but collected and remitted by the business. When you sell goods or provide services, you collect output VAT from customers; when you purchase goods or services for the business, you pay input VAT. At filing time, you report the difference between output VAT and input VAT to the National Tax Service (NTS) and pay (or get refunded) the balance. The complication is that the filing cycle and method are structured completely differently depending on the type of taxpayer.
Corporations file four times a year (Period 1 preliminary and final, Period 2 preliminary and final). Individual general taxpayers file, in principle, twice a year, since their preliminary filings are replaced by preliminary tax notices issued by the NTS rather than self-filed returns. Simplified taxpayers file, in principle, only once a year. On top of that, simplified taxpayers who are required to issue tax invoices must file an additional return for the first half of the year in July. Missing these distinctions and assuming "I didn't file last year and nothing happened" is a common way business owners end up receiving a penalty notice.
2. VAT Filing Structure by Taxpayer Type: Preliminary vs. Final Filing
Korea's VAT taxable period splits the year into Period 1 (January–June) and Period 2 (July–December), and each period is further divided into a preliminary filing and a final filing.
Corporations must file both a preliminary and a final return for each period. After reporting and paying based on the preliminary period's results, the final filing settles the remaining balance for the full half-year, net of what was already paid in the preliminary filing.
Individual general taxpayers are not required to file a preliminary return. Instead, the NTS calculates 50% of the tax paid in the previous taxable period and sends a preliminary tax notice in April and October, which the taxpayer simply pays. Whatever is paid through this preliminary notice is automatically deducted at the subsequent final filing. However, if actual sales have dropped significantly (for example, due to a business slowdown), a taxpayer can opt to calculate and file a preliminary return instead of paying the notice amount as-is.
Simplified taxpayers treat the entire calendar year (January–December) as a single taxable period and, in principle, file and pay only once, in January of the following year. That said, a simplified taxpayer whose total supply value in the prior year reached 48 million KRW or more is required to issue tax invoices, and must additionally file a return for the January–June portion (the "preliminary assessment period") in July. It is also easy to overlook that simplified taxpayers with annual supply value under 48 million KRW are exempt from the VAT payment itself, but the filing obligation still applies.
3. 2026 VAT Filing and Payment Deadlines at a Glance
The standard filing deadlines fall on April 25, July 25, October 25, and January 25 of the following year each year, but any date that lands on a Saturday, Sunday, or public holiday automatically rolls forward to the next business day. In 2026, three of the four regular deadlines fall on a weekend and are pushed to the following Monday.
| Taxpayer Type | Filing | Period Covered | Standard Deadline | Actual 2026 Deadline |
|---|---|---|---|---|
| Corporation / Individual general taxpayer | Period 1 preliminary | Jan 1–Mar 31, 2026 | Apr 25 | Apr 27 (Mon) (Apr 25 falls on Saturday) |
| Corporation / Individual general taxpayer | Period 1 final | Jan 1–Jun 30, 2026 | Jul 25 | Jul 27 (Mon) (Jul 25 falls on Saturday) |
| Corporation / Individual general taxpayer | Period 2 preliminary | Jul 1–Sep 30, 2026 | Oct 25 | Oct 26 (Mon) (Oct 25 falls on Sunday) |
| Corporation / Individual general taxpayer | Period 2 final | Jul 1–Dec 31, 2026 | Jan 25, 2027 | Confirm the exact date via the NTS notice closer to the date |
| Individual general taxpayer (preliminary notice) | Preliminary notice payment | 50% of prior period's tax paid | April / October | Notice issued in the same month as the preliminary filing |
| Simplified taxpayer | Regular annual filing | Jan 1–Dec 31, 2025 | Jan 25, 2026 | Deadline already passed (reference only) |
| Simplified taxpayer (tax-invoice-issuing) | Preliminary assessment period filing | Jan 1–Jun 30, 2026 | Jul 25 | Jul 27 (Mon) (same as Period 1 final) |
Remembering just one structural rule removes most of the confusion: a preliminary filing reflects only that quarter's results, while a final filing settles the full half-year, netting out whatever was already reported or paid in the preliminary stage. Individual general taxpayers in particular should remember: you don't need to file a preliminary return yourself, but you absolutely must pay the amount on the notice.
4. Missed the Deadline? How VAT Penalties Are Calculated and What to Do
Missing a deadline can trigger up to three separate types of penalty tax, depending on the situation.
- Failure-to-file penalty: If you don't file at all, 20% of the tax due is added as a penalty, rising to as much as 40% if the omission is found to involve intentional concealment, such as deliberately hiding sales.
- Under-reporting penalty: If you filed but reported less tax than you actually owed, 10% of the shortfall is added.
- Late-payment penalty: Regardless of whether you filed on time, any unpaid tax accrues an additional 0.022% per day it remains unpaid. Even a single month of delay adds roughly 0.66% to the tax due, so the cost compounds the longer you wait.
Because the failure-to-file penalty and the late-payment penalty are applied together, the total burden can snowball quickly if a filing is missed entirely. Still, filing late voluntarily (a so-called after-the-deadline filing) reduces the penalty: filing within one month of the statutory deadline reduces the failure-to-file penalty by 50%, filing within one to three months reduces it by 30%, and filing within three to six months reduces it by 20%. In short, filing as soon as you realize you missed the deadline is the single most effective way to limit the damage. Issuing a tax invoice late or missing an input tax credit can also trigger separate penalties or disadvantages, so it is worth cross-checking your sales and purchase records on Hometax once more before you file.
5. Frequently Asked Questions (FAQ)
Q1. My preliminary tax notice as an individual general taxpayer doesn't match my actual sales this quarter. Do I have to pay it as-is?
The preliminary notice amount is based on your prior taxable period's results, so if your sales have dropped sharply or you temporarily closed the business, the notice can diverge significantly from reality. In that case, you can choose to calculate the actual period's results yourself and file a preliminary return instead — doing so cancels the preliminary notice. If sales have fallen sharply, switching to a preliminary filing is often more favorable than simply paying the notice amount.
Q2. I'm a simplified taxpayer who has never issued a tax invoice. Do I still need to file in July?
If your total supply value in the prior year was under 48 million KRW, you have no tax-invoice-issuing obligation and therefore no July preliminary assessment filing obligation either — you only need to file once, in January of the following year. However, the moment your cumulative supply value crosses that threshold, both the invoice-issuing obligation and the July filing obligation kick in, so it's worth tracking your cumulative supply value periodically if your sales are growing.
Q3. Since deadlines that fall on a weekend roll over to the next business day, can I just prepare at a more relaxed pace?
It's true you gain a bit of extra time, but last-minute variables — Hometax server congestion, delayed document preparation — are always a risk. Rather than treating the rolled-over deadline as your real target, aim to have your sales and purchase records organized around the original 25th of the month; that buffer gives you time to catch and fix unexpected errors or missing data.
Q4. If my input VAT is higher than my output VAT, do I not need to pay anything?
If input VAT exceeds output VAT, the difference results in a refund rather than a payment. However, a refund filing still has to be submitted within the regular filing deadline to be processed normally — missing the deadline can delay the refund or trigger additional verification steps. Even if you expect a refund, don't assume "there's no tax to pay so I don't need to file" — filing by the deadline is still required.
6. Estimate Your VAT Payment and Get Ready to File
Knowing the exact filing deadline doesn't help much if you have no sense of how much you'll actually owe this period, which makes it hard to prioritize what records to prepare first. The VAT Calculator lets you enter your output and input VAT to instantly see an estimated payment (or refund) amount, so you can gauge the expected tax and plan your cash flow before filing officially through Hometax.
If you also own real estate and need to keep the property tax calendar in mind, the Apartment Property Tax Calculation Guide is a useful companion read. Rather than scrambling to handle everything right before the deadline, building the habit of estimating your tax and organizing your records well in advance is the most reliable way to avoid penalty tax altogether.
