With no establishment and no Korean business registration, the e-Tax invoice system doesn't reach you – selling into South Korea from abroad doesn't by itself create invoicing duties. Digital-service sellers should check the simplified VAT registration rules, which are a separate regime.

Foreign suppliers of digital services registered under Korea's simplified VAT scheme file and pay through that regime without issuing e-Tax invoices, per the sources read. If your registration is the simplified kind, the mandate shouldn't reach you – but a branch or other taxable presence changes the answer, so confirm with the NTS or a local adviser.

Every corporation issues e-Tax invoices regardless of size. For individual entrepreneurs the line is prior-year turnover of KRW 80 million – above it, you're in (since July 2024); below it, e-Tax invoicing is voluntary, per the sources read. The threshold has stepped down repeatedly, so sole traders near the line should expect it to keep falling. Hometax issues invoices free of charge.

Corporations have issued e-Tax invoices since January 2011 – NTS XML with a PKI signature, transmitted within one day of issuance (monthly fallback by the 10th). The system is mature; the compliance risk is operational, since the graduated penalties (0.3–2% of supply value) attach to late transmission and non-issuance, per the sources read.