Korean tax invoice: required entries and the electronic form

The four mandatory entries

On a Korean tax invoice the "mandatory entries" are the ones whose absence or inaccuracy puts the validity of the document itself in question. Article 32 of the VAT Act sets out four of them, and no amount of detail elsewhere substitutes for any one of them.

In practice the two that go wrong most often are the recipient's registration number and the date of preparation. Copying a previous document carries the old registration number forward while the date changes, so the error appears quietly on the first invoice to a different customer.

• The supplier's registration number and name — the name on the registration certificate, not a familiar short form.
• The recipient's registration number — where the customer is not a business, their assigned number or resident registration number takes this place.
• The supply value and the VAT amount — a single combined total does not satisfy this; the two figures are shown separately.
• The date the invoice was prepared — a different entry from the supply date, which is optional.

The optional entries are what prevent disputes

The supplier's address, the recipient's trade name and address, both parties' business type and category, the items supplied, unit prices and quantities, the supply date and the type of transaction are all optional. Leaving them out does not invalidate the document.

They are also precisely the entries a later argument about "what was this payment for" turns on. An invoice that satisfies the requirements while showing only a total does not explain the transaction.

Issuing and transmitting the electronic form

Corporations have had to issue electronic tax invoices since January 2011. A sole proprietor is subject to the same obligation when the previous year's supply of goods and services at the place of business, taxable and exempt together, totals KRW 80 million or more; the National Tax Service applies that figure from July 2024 (read on 6 October 2026). It was KRW 100 million from July 2023 and KRW 200 million from July 2022.

The obligation starts with the second VAT period of the year after the threshold is reached. If the 2025 total was KRW 90 million, for example, the sole proprietor must issue electronic tax invoices from 1 July 2026. The threshold has been lowered several times, so confirm the figure with the National Tax Service each year.

An invoice is normally issued at the time of supply. A monthly aggregate tax invoice covering one customer may be issued up to the tenth day of the following month. Details of an issued electronic tax invoice must be transmitted to the National Tax Service by the day after issue.

Correcting one that has already been issued

Treating an issued tax invoice as if it had never existed and writing a fresh one is not the normal route. A mistaken entry, a supply value that changes later, returned goods and a cancelled contract each have their own form of corrected tax invoice.

The reason determines the preparation date of the correction, and therefore which tax period it lands in. Some reasons call for reversing the original with a negative entry and issuing again; others call for issuing only the difference. Settle which reason applies before choosing how to issue.

A tax invoice and an exempt-supply invoice are different documents

A taxable supply takes a tax invoice; an exempt supply takes the separate exempt-supply invoice. The names are close enough that one template gets edited into the other, and an exempt supply that goes out showing a VAT amount has to be corrected afterwards.

Zero-rated supplies are not exempt — they are taxable at a rate of 0%. They take a tax invoice showing zero tax, and whether zero rating applies depends on the nature of the transaction, so confirm it before issuing.