Tax Invoice Number Validator
Validate Thai tax invoice numbers for RD e-Filing compatibility in real time. Checks maximum 35 characters, allowed symbols, and no-space rule per VAT Announcement No. 39.
Tax Invoice Number Validator
Allowed Characters
A-Z, a-z, 0-9 and symbols - / _ . ( ) # & +
Max 35 characters, no spaces
Common Format Examples
Click an example to test it
Reference: RD Announcement on VAT No. 39 — Invoice number must be unique within one tax period
Thai Tax Invoice Number Rules (RD)
Maximum 35 characters
Per VAT Announcement No. 39 and e-Tax Invoice system requirements.
Allowed: A-Z, a-z, 0-9
Latin letters (upper and lower case) and Arabic numerals are always allowed.
Allowed symbols: - / _ . ( ) # & +
These 9 symbols are explicitly permitted. All other symbols (including Thai characters) are not.
No spaces
Spaces are not allowed anywhere in the invoice number.
Must be unique per tax period
Each invoice number must be unique within one VAT return period (monthly). Duplicates in the same PP.30 filing will cause rejection.
This tool validates format only, not whether the invoice number is already registered or unique in the RD system. For official verification, check via RD e-Tax Invoice portal or consult your accountant.
Need help with VAT filing and e-Tax Invoice?
WACC Service handles monthly VAT (PP.30) filings, e-Tax Invoice setup, and tax compliance for Thai SMEs nationwide.
Contact WACC