Invoice Number Format Checker

Checks a sample invoice number against GST Rule 46(b)'s character-set and 16-character length rules.

What this can't check from one example: Rule 46(b) also requires the FULL series (across the whole financial year) to be consecutive with no gaps and unique for that financial year. Those are properties of every invoice you issue, not of one sample string — you have to verify them against your actual numbering as you go (or use a tool that locks the format and allocates numbers atomically, so a gap can't occur).

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BillForge creates GST invoices with the tax already worked out — gap-free Rule 46 numbering, GSTR-1 & 3B export, TDS records. Free for 3 months, no card needed. Your CA should still review what you file.

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Frequently asked questions

What does GST Rule 46(b) actually require?

Rule 46(b) of the CGST Rules requires a consecutive serial number, not exceeding sixteen characters, in one or multiple series, unique for a financial year — containing only alphabets, numerals, and the special characters hyphen (-) and slash (/), in any combination.

Can I use a symbol like # or _ in my invoice number?

No. Rule 46(b) only permits letters, numbers, hyphens (-) and slashes (/). A number like "INV#001" or "INV_2026_001" doesn't meet the rule, even though many billing tools will let you type it.

Why can't this tool check if my numbering is "sequential" or "unique"?

Those are properties of your ENTIRE series across a financial year — invoice 47 has to be exactly one more than invoice 46, with no gaps and no repeats — not something you can verify from a single example number. You'd need to check your actual issued invoices, or use software that allocates numbers atomically so a gap can never happen.

What happens if I change my invoice number format mid-year?

It's legal to start a new series, but changing an EXISTING series mid-year risks creating a gap or duplicate, which GST auditors specifically look for. BillForge locks your number format automatically after your first invoice of a financial year, for exactly this reason.

Is this invoice number checker free?

Yes, completely free with no login.

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