Resources

GSTIN format on invoices

A GSTIN is 15 characters: state code, PAN, entity number, Z, and a check digit. Format checks catch typos. They are not a GST portal registration lookup.

Educational summary. Not legal, tax, or filing advice. Confirm with the notified GST law and your Chartered Accountant.

The 15 characters

Positions 1–2 are the state code. Positions 3–12 are the PAN. Position 13 is the entity number. Position 14 is typically Z. Position 15 is a check character. One Stop Invoice validates that shape as you type.

What validation is not

A format check is not proof that the GSTIN is active on the GST portal. We do not claim live GSTN authentication on every keystroke as a government API.

Related product pages: GST invoicing , invoice generator , CA Sync .