Why isn’t the VAT 10% of the gross amount?

The 10% rate applies to the net amount before VAT is added. The gross amount is 110% of the net amount, so the VAT it contains is 10/110 of the gross amount, that is, one eleventh. A gross amount of 110,000 won splits into a net amount of 100,000 won and VAT of 10,000 won.

How are small odd amounts like 5 or 15 won rounded?

The VAT on a net amount of 5 won is exactly 0.5 won, so it is shown as 1 won with a gross amount of 6 won. A net amount of 15 won gives VAT of 2 won and a gross amount of 17 won. Odd amounts are not always rounded up; a fraction rounds up only when it is 0.5 won or more. Splitting a gross amount of 5 won gives a net amount of 5 won and VAT of 0 won. From the gross amount the exact value is a fraction over 11, so an exact 0.5 won boundary does not occur with whole-won inputs.

Why isn’t simplified taxation supported?

Tax payable under simplified taxation depends on industry value-added ratios, credits and other rules, so it cannot be found by adding 10% to a single amount or dividing a total by 1.1. This page calculates only the net amount and VAT for transactions at the standard 10% rate; it does not classify taxpayers or calculate return or refund amounts.

Can I enter the combined amount of several items?

You can calculate a single combined amount, but the result is not guaranteed to match per-item calculations. Two items with a net amount of 5 won each give 1 won of VAT each, 2 won in total, while a combined net amount of 10 won calculated once gives 1 won of VAT. Per-item rounding, mixed rates and totals that include exempt amounts are not supported. Check the rules of your issuing system for actual document totals.

Are the amounts I enter or the results saved?

The amounts you enter and the results are not saved on the server or in browser storage. The state just before a reset is kept briefly in the page’s memory so you can undo, and is cleared on new input, a mode change or leaving the page. Copied result text may remain on your device’s clipboard. See the privacy policy in Korean for how personal data is handled.

Korean VAT calculator

Enter a net amount or a VAT-inclusive gross amount to calculate the net amount, VAT and gross amount at South Korea’s standard VAT rate of 10%.

From the net amount From the gross amount

Net amount (before VAT) won Enter the amount before VAT is added.

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Enter the amount in won as a whole number, like 1000.

How Korean VAT is calculated and what is supported

This calculator handles amounts for transactions subject to South Korea’s standard value-added tax rate of 10%. It follows the National Tax Service’s guidance on the general taxpayer rate and does not determine the tax status of a transaction or business.

Let S be the net amount, V the VAT and T the gross amount. From the net amount: V = S/10 and T = 11S/10. From the gross amount: S = 10T/11 and V = T/11. The VAT included in a gross amount is one eleventh of it, not 10%.

Exact fractions are kept during the calculation, and each result is rounded to the nearest won only once, when it is displayed. Rounding is ROUND_HALF_UP: a fraction of 0.5 won or more rounds up, less than 0.5 won rounds down. A net amount of 5 won is shown as VAT 1 won and gross amount 6 won. This rounding is semku’s display policy, not a statutory method that applies to every tax document.

The displayed net amount, VAT and gross amount are never reused to calculate or reverse-calculate another result. When you switch the basis, the number you entered is recalculated on the new basis. Re-entering a rounded result by hand can differ from the original exact internal value.

The input is a single whole-won amount from 0 to 1,000,000,000,000,000 won. The limit applies to the input; results above it are not truncated. An empty field means waiting for input, and 0 won gives 0 won for all three items.

Simplified taxation, zero-rating, exemptions, multiple rates and totals across several items are not supported. Tax-return amounts, payable and refundable tax, input-tax credits, penalties and filing deadlines, taxpayer classification, returns, negative transactions and foreign currency are not calculated either. If you enter an amount that already combines several items, 10% is applied to that single amount; per-item tax is not summed. Two items of 5 won each give 1 won of VAT each, 2 won in total, whereas a combined net amount of 10 won calculated once gives 1 won of VAT.

Results may differ from tax invoices and other documents depending on how the issuing system handles fractions of a won and per-item totals. Check the rules of the system you use for the actual document amounts. This result is a reference for checking transaction amounts and does not replace a tax return or the issuing of a tax document.

Rate source: National Tax Service of Korea — VAT overview (in Korean) · checked 2026-09-10

Korean VAT calculation rules v1 · 2026-09-10

Frequently asked questions

Why isn’t the VAT 10% of the gross amount?: The 10% rate applies to the net amount before VAT is added. The gross amount is 110% of the net amount, so the VAT it contains is 10/110 of the gross amount, that is, one eleventh. A gross amount of 110,000 won splits into a net amount of 100,000 won and VAT of 10,000 won.
How are small odd amounts like 5 or 15 won rounded?: The VAT on a net amount of 5 won is exactly 0.5 won, so it is shown as 1 won with a gross amount of 6 won. A net amount of 15 won gives VAT of 2 won and a gross amount of 17 won. Odd amounts are not always rounded up; a fraction rounds up only when it is 0.5 won or more. Splitting a gross amount of 5 won gives a net amount of 5 won and VAT of 0 won. From the gross amount the exact value is a fraction over 11, so an exact 0.5 won boundary does not occur with whole-won inputs.
Why isn’t simplified taxation supported?: Tax payable under simplified taxation depends on industry value-added ratios, credits and other rules, so it cannot be found by adding 10% to a single amount or dividing a total by 1.1. This page calculates only the net amount and VAT for transactions at the standard 10% rate; it does not classify taxpayers or calculate return or refund amounts.
Can I enter the combined amount of several items?: You can calculate a single combined amount, but the result is not guaranteed to match per-item calculations. Two items with a net amount of 5 won each give 1 won of VAT each, 2 won in total, while a combined net amount of 10 won calculated once gives 1 won of VAT. Per-item rounding, mixed rates and totals that include exempt amounts are not supported. Check the rules of your issuing system for actual document totals.
Are the amounts I enter or the results saved?: The amounts you enter and the results are not saved on the server or in browser storage. The state just before a reset is kept briefly in the page’s memory so you can undo, and is cleared on new input, a mode change or leaving the page. Copied result text may remain on your device’s clipboard. See the privacy policy in Korean for how personal data is handled.

Privacy on this page

Calculations run in your browser. The amount you enter is not sent to the server or saved in browser storage. Reloading the page returns the input to its initial state.

To understand how the page is used and to improve the service, this page sends semku’s own usage statistics and automatic error reports. They go only to the dedicated endpoint under semku.com/api/telemetry/v1/. They are not used for advertising or third-party tracking.

The usage statistics include the stage of use (such as starting an operation or requesting a copy), the time it happened and fixed identifiers that distinguish the page and feature. They do not include the amount you enter, the results shown or the text you copy. Inputs are not sent as hashes or as size categories either. The full URL and search terms are not sent.

Operations and sessions are distinguished by randomly generated identifiers. In the browser these exist only in temporary memory and are not written to cookies or browser storage. No identification based on cookies or combined device characteristics is used.

Error reports contain the error type, code and time, and, where available, a registered program-source identifier with the line and column number. The error message text and stack traces are not sent. Usage statistics and error reports also carry the site identifier, the published build and a random record identifier. IP addresses and user-agent strings are not part of these items.

The feedback form sends the rating you chose and the text you typed in the free-text field when you press the send button. A random ID that distinguishes the submission, the page, site and published build, and the type of request are also sent. There are no fields for your name, email address or phone number, and the amount you enter are not attached automatically. Whatever you write in the free-text field is sent as is. Please do not enter personal data, passwords, authentication keys or payment details.

Separately, when you visit the site, the hosting provider records your IP address, the time of the request and user-agent information about your browser and device in Cloudflare Pages’ standard access logs.

For details, see the privacy policy in Korean.

Calculations run in your browser without sending the amounts you enter to the server or storing them. Results are a reference for transactions at the standard Korean VAT rate of 10% and do not replace a tax return or a tax invoice.