Qualified Invoice System: all JCT-registered businesses issuing invoices to business customers (B2B/B2G) — registration is required to let your customers claim input JCT. Peppol/JP PINT adoption is voluntary and market-driven for B2B. Small businesses below the JPY 10 million taxable-sales threshold may stay unregistered but then their customers lose (part of) the input credit.
Do not tell a client Japan 'has e-invoicing since 2023' — they will scope a Peppol project for an obligation that does not exist, and miss the ones that do: the Qualified Invoice content/retention rules and the Electronic Books Preservation Act (electronically received data must be kept electronically since 1 Jan 2024). The near-term live issue is the transitional input-credit relief for purchases from non-registered suppliers stepping down from 80% to 50% — on the current published schedule that happens 1 Oct 2026, i.e. roughly ten weeks out. Confirm against the NTA before advising.
3 of 3 are primary sources. Mandate dates move — treat this page as a starting point and confirm against the primary source before committing a plan.
A page is a starting point. A scoped analysis gives you the specification, the mapping and the effort — in weeks, not quarters.