Invoicing in Korea: what foreign founders need to get right

Korean invoicing obligations follow the registered supplier, the customer, and the nature and timing of the supply. A foreign founder operating a Korean company does not use a different tax-document rule merely because the client conversation happens in English.

First identify whether the seller is a Korean corporation or individual business, whether the supply is taxable, exempt, zero-rated, or outside Korean VAT, and whether the customer is domestic or overseas. Those facts decide the statutory route; the preferred language of the commercial invoice does not.

Operational shortcut: classify the supply first, then choose the client document and the Korean tax document separately.

An overseas customer may need an English commercial invoice to approve the work, book the payable, arrange foreign-currency transfer, and match the payment reference. It should be legible to a finance team that does not use HomeTax.

A Korean electronic tax invoice is a statutory VAT record created and delivered by an approved electronic method, then transmitted to the National Tax Service. It is not simply the commercial PDF uploaded somewhere later.

The two records can coexist. When they do, keep the parties, supply description, dates, currency basis, and amount reconciled so the commercial, bank, tax, and accounting evidence tells one story.

Show the Korean seller’s registered name, address, and business registration number together. Identify the customer’s legal name, billing address, and finance contact, then describe the delivered goods or services in plain language.

Use a stable invoice number and distinguish the supply date, issue date, and due date. State quantity, unit price, currency, subtotal, tax treatment where relevant, total, purchase-order or contract reference, and payment terms.

For the bank route, use the beneficiary name expected by the bank, account details, SWIFT information where needed, and a transfer reference that can be reconciled to the invoice. Agree who bears intermediary and receiving-bank fees.

Korean corporations are within the mandatory electronic tax-invoice regime. The National Tax Service also applies the mandate to individual businesses that meet the current turnover test; from July 2024 the published threshold is KRW 80 million based on the prior year’s per-business-place taxable and exempt supplies.

Thresholds and detailed application dates can change, and special transaction rules still matter. Confirm the business’s current status in HomeTax, NTS guidance, or with a qualified Korean tax adviser instead of relying on a previous year’s invoice template.

Being an electronic issuer does not mean every receipt, consumer sale, exempt supply, export, or cross-border service uses the same tax invoice. Classify the transaction before choosing the document.

The general rule ties tax-invoice issuance to the time goods or services are supplied. The legally relevant supply time may not be the date a founder sends a PDF, receives customer approval, or sees cash in the bank.

A monthly aggregate rule can permit one tax invoice for qualifying supplies to the same customer, issued by the 10th day of the following month. Treat that as a defined exception, not as a universal grace period for late invoicing.

If the 10th is a Saturday or public holiday, NTS guidance moves the deadline to the next business day. Document why the aggregate method applies and keep the underlying transaction schedule.

Electronic issuance is complete when the signed standard electronic file reaches the recipient’s designated mailbox or the NTS issuance system. A text alert, link, unsigned file, or ordinary emailed PDF does not by itself complete electronic tax-invoice issuance.

After issuance, the record generally must be transmitted to NTS by the next day. HomeTax issuance can combine the operating steps, while an ERP or registered service provider may expose issue and transmission as separate events.

Reconcile both statuses. A customer receiving a view of the invoice does not prove NTS transmission, and a transmitted tax record does not prove the overseas customer approved or paid the commercial invoice.

NTS lists HomeTax, registered ASP providers, and standard-certified ERP systems as electronic issuance methods. The right route depends on volume, approvals, accounting integration, access controls, correction handling, and the evidence available after transmission.

Assign who can issue, who reviews party and VAT data, who monitors rejection or transmission errors, and who can create a corrected tax invoice. Do not share a founder’s personal authentication route as an informal team workflow.

Test exports and reconciliation before volume grows. The system should preserve the issue identifier, recipient, supply date, amounts, transmission status, corrections, and the accounting entry tied to the transaction.

Billing in USD or receiving foreign currency does not automatically make a supply zero-rated. Determine the customer, place and type of supply, performance or use location, and the statutory basis before selecting VAT wording.

Where zero rating is claimed, NTS rules require supporting documents with the VAT filing. Depending on the transaction, evidence may include export records, a service contract, foreign-currency receipt evidence, or other prescribed proof.

Keep the English commercial invoice, contract, delivery or performance evidence, exchange-rate record, bank advice, tax analysis, and any electronic tax-invoice record connected. Cross-border evidence is strongest when it reconciles rather than merely accumulates.

If the supply is cancelled, returned, repriced, or the original document contains an error, determine whether a corrected electronic tax invoice is required. Do not silently replace a final client PDF or overwrite the accounting record.

Preserve the original document, the reason for correction, the corrected record and transmission result, customer communication, settlement adjustment, and accounting treatment. The chain should explain what changed and when.

Retention duties vary by record and legal basis. Set the archive policy with a Korean adviser, and ensure provider exports remain readable and attributable after a software or accountant change.

Do not treat an English PDF as the electronic tax invoice. Do not use the 10th as a universal deadline. Do not equate client receipt with NTS transmission. Do not assume foreign currency creates zero rating. Do not overwrite an issued record to correct it. Do not let bank, accounting, and tax amounts drift apart.

A reliable workflow is intentionally plain: classify the supply, create the right records, issue on the correct clock, confirm transmission, match the payment, and retain the evidence behind every decision.