Invoice Requirements in South Korea: Legal Rules for 2026

TL;DR: South Korea requires e-tax invoices issued through the NTS system for most B2B transactions, with 10% VAT and mandatory business registration numbers. E-tax invoices must be transmitted to NTS by the day after issuance -- retain records for at least five years.

South Korean VAT (부가가치세) relies heavily on electronic tax invoicing through the National Tax Service (NTS) ecosystem for many B2B flows. Corporate buyers expect structured issuance that their ERP can ingest; a casual PDF may not qualify as the statutory evidence chain. 2026 operations should treat invoice data as return-ready, not “finance will fix it later.” This overview is general information, not legal advice—confirm zero-rated exports, services to non-residents, and simplified regimes with the NTS or your Korean tax adviser. Chaebol-style shared service centres often impose extra GL codes on e-tax exports—negotiate fields before you integrate APIs.

Required fields

Electronic tax invoices (e-tax invoices) and related documents carry supplier business registration number, buyer identifiers where required, serial identifiers, dates, line descriptions, taxable value, VAT rate and amount, and totals. Credit notes must reference original issuances and adjust VAT consistently. English summaries may appear for foreign parents but statutory Korean fields govern compliance.

Tax rules (VAT/GST/sales tax rates)

The standard VAT rate is 10%. Zero-rated exports and certain foreign services depend on place of supply and documentation. Exempt supplies must not show recoverable VAT improperly. Mixed transactions need line clarity so buyers can reconcile deductions. Head-office / branch billing must mirror business registration hierarchies so e-tax identifiers match withholding receipts and VAT returns. Free-trade-zone adjacent logistics can create edge cases for place of supply—archive contracts beside e-tax XML when auditors trace services across borders.

Language requirements

Korean is mandatory for official e-tax fields and NTS reporting. English may supplement contracts but cannot replace Hangul labels required on statutory outputs.

Digital invoicing rules

Issuance typically flows through NTS-connected software or service providers—archive XML/JSON, PDF renditions, and acknowledgement logs. Immutable storage supports VAT audits and transfer pricing reviews that reference invoice trails. ERP postings should include e-tax serial keys in memo fields so finance shared services can reconcile AP batches without opening raw JSON daily. Time-zone stamps matter for month-end closes when HQ sits outside Korea—use consistent UTC logging internally, local presentation externally.

Invoice numbering rules

E-tax invoices carry serial identifiers assigned through the NTS-connected issuance system. The system enforces uniqueness per business registration number and tax period. While the numbering is largely system-generated, businesses should maintain internal cross-reference numbers in their ERP that link e-tax serial identifiers to accounting entries and customer records. Credit notes (수정세금계산서, corrective tax invoices) must reference the original e-tax invoice and carry their own identifiers. Businesses operating multiple branches under different business registration numbers should ensure each branch’s numbering is traceable to the correct registration. Manual overrides or offline numbering outside the NTS system should be avoided -- treat the e-tax issuance platform as the authoritative numbering source. For internal tracking purposes, you may use additional alphanumeric references alongside the NTS-assigned serial.

Common exemptions and special cases

Simplified tax invoices may be issued by businesses providing goods or services to final consumers (such as retail, food service, and personal services) -- these require fewer details than full e-tax invoices and may be issued through POS systems connected to NTS. Small businesses with annual turnover below specified thresholds (the threshold varies and has been adjusted -- check current NTS guidance) may qualify for simplified taxation that reduces VAT obligations. Zero-rated exports and certain services for non-residents require supporting documentation but no Korean VAT charge. Exempt supplies include basic unprocessed food, medical and health services, educational services, and certain financial and insurance services -- these must not show VAT. Reverse charge applies to certain services received from foreign suppliers by Korean businesses. Free-trade zone and bonded area transactions have specific rules for VAT treatment. Withholding taxes on domestic services (such as professional fees and rent) operate alongside VAT and must be separately documented -- withholding tax receipts should be traceable to the related e-tax invoice for audit consistency.

Record retention requirements

Korean tax law requires retention of tax invoices and accounting records for five years from the statutory filing deadline for the relevant tax period (some sources cite the period from the end of the fiscal year). The Commercial Act may require ten years for certain accounting books. E-tax invoice data is retained by NTS in their system, but businesses must also maintain their own copies of XML/JSON data, PDF renditions, and acknowledgement logs. Records must be accessible for NTS audits and should be in Korean or readily translatable. Electronic storage is the norm given the e-tax invoice system, but ensure your archiving solution meets immutability and accessibility requirements. For businesses subject to transfer pricing documentation, invoices supporting intercompany transactions should be retained alongside the transfer pricing report for the required period. Destroying records prematurely can result in penalties and adverse presumptions during tax examinations.

E-invoicing status

South Korea has one of the most established mandatory e-tax invoice systems globally. E-tax invoices (전자세금계산서) have been mandatory for corporations since 2011 and for individual business operators with revenue above specified thresholds since 2012 (the threshold has been progressively lowered to approximately KRW 80 million, though check the latest NTS notice). E-tax invoices are issued through NTS-certified software or service providers and must be transmitted to NTS by the day after issuance. The NTS HomeTax portal also allows manual issuance for low-volume taxpayers. The system assigns a unique confirmation number to each transmitted invoice. NTS uses the e-tax invoice data for automated cross-matching between buyers and sellers, pre-filled VAT returns, and risk profiling. The data is also used for cash receipt (현금영수증) verification alongside consumer-facing transactions. Korea’s system has been operational for over a decade and is highly mature, with near-universal adoption among B2B traders. The NTS continues to refine the system, expanding data integration with corporate tax, withholding tax, and customs reporting.

Penalties

The NTS may impose penalties and surcharges for late issuance, omissions, or incorrect VAT linked to non-compliant documents. Failure to issue an e-tax invoice when required attracts a penalty of 2% of the supply value. Late issuance (after the deadline but within the same or following tax period) carries a reduced penalty of 1% of the supply value. Late transmission to NTS (issuing on time but transmitting late) attracts a penalty of 0.5% of the supply value. Failure to transmit to NTS at all carries 0.5% to 1% of the supply value. For the buyer, failure to receive a proper e-tax invoice can result in denial of input tax deduction -- a 0.5% penalty may apply if the buyer accepts goods or services without obtaining a valid e-tax invoice. Under-reporting of VAT on returns triggers a general understatement penalty of 10% of the additional tax due, which increases for deliberate understatement. Interest accrues on late-paid tax at rates set by NTS (typically in the range of 2.2% per annum for the initial period, plus higher rates for extended delays). Customers may block payment when e-tax data fails validation; contractual SLAs can stack on top of statutory penalties when issuance misses buyer cut-offs.

In practice, treat invoice issuance as part of your month-end close: reconcile e-tax serials to revenue journals before group consolidation. Document escalation paths when e-tax APIs fail during month-end -- tax law timelines rarely forgive vendor outages.

FAQ

Is e-tax invoicing mandatory for all businesses in South Korea? E-tax invoices are mandatory for all corporations regardless of size and for individual business operators with annual revenue exceeding approximately KRW 80 million (check the latest NTS notice, as this threshold has been lowered over time). Businesses below the threshold may still issue e-tax invoices voluntarily, and many do so because buyers prefer the automated cross-matching capability.

What is the deadline for transmitting e-tax invoices to NTS? E-tax invoices must be transmitted to NTS by the day after issuance. For example, an invoice issued on March 15 must be transmitted by March 16. Late transmission attracts a penalty of 0.5% of the supply value. Note that issuance and transmission are separate steps -- you may issue the invoice to the buyer first and then transmit the data to NTS, as long as transmission occurs by the next day.

How do corrective tax invoices work? If you need to correct a previously issued e-tax invoice (due to returns, price changes, or errors), you issue a corrective tax invoice (수정세금계산서) that references the original. There are specific reason codes for different types of corrections (returns, contract changes, errors in the original, etc.). The corrective invoice must be transmitted to NTS just like the original. For the buyer, the correction adjusts their input tax credit accordingly.

Can foreign companies issue e-tax invoices in South Korea? Foreign companies that have a permanent establishment or business registration in South Korea must issue e-tax invoices through the NTS system for their Korean B2B transactions. If you do not have a Korean business registration, your Korean customers may need to issue self-assessment documents for VAT purposes. Non-resident providers of digital services to Korean consumers may have separate registration and invoice obligations -- consult a Korean tax adviser for your specific situation.

Template link

Use our South Korea invoice template alongside your e-tax solution for human-readable layouts. Read the invoice tax compliance guide and tax rate lookup tool. Official references include the National Tax Service (English) and Hometax. Join InvoiceQuickly early access to coordinate Korean VAT invoicing with your APAC footprint.