Checksum first, registry next

🪪 Tax ID Validator & Lookup

Validate a Vietnamese tax ID (10 or 13 digits) against its official weighted checksum with every multiplication shown, then press Look up to fetch the registered name, address and operating status.

Tax ID — 10 digits, or 13 as NNNNNNNNNN-NNN

Checksum rule: N₁₀ = 10 − (31·N₁+29·N₂+23·N₃+19·N₄+17·N₅+13·N₆+7·N₇+5·N₈+3·N₉) mod 11. The tax ID is only sent to the public registry API when you press Look up (xinvoice.vn, limit ~10 lookups / 30s).