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About this tool
Build a consecutive tax invoice numbering series for a financial year and check it against the 16-character limit in Rule 46(b).
This generator builds a tax invoice numbering series for an Indian financial year and checks it against Rule 46(b) of the CGST Rules, 2017, which requires a consecutive serial number of not more than sixteen characters made up only of letters, digits, hyphen and slash, unique for the financial year. It also flags numbers the e-invoice schema would reject, such as one beginning with 0, / or -. Aimed at business owners and accountants setting up a numbering scheme on 1 April.
Open GST Invoice Series Generator on AltFTool — it loads instantly in your browser.
Provide your input — an image, text, or data.
Let the tool analyze or generate the result.
Review, refine, and reuse the output wherever you need it.
Shows how many of the sixteen characters each number uses and how many are spare.
Warns when the number starts with a character the e-invoice schema rejects.
Tells you how many invoices fit before the padded digits widen the number.
Sixteen characters. Rule 46(b) of the CGST Rules, 2017 requires a consecutive serial number not exceeding sixteen characters, so INV/2025-26/0001 is exactly at the limit while INVOICE/2025-26/0001 is four characters over.
Only the hyphen and the slash, alongside letters and numerals. Rule 46(b) names them expressly, so a hash, space, underscore, full stop or hash symbol makes the invoice number non-compliant.
Yes. Rule 46(b) permits one or multiple series, so separate books for branches, export sales or B2C counters are allowed provided each series is consecutive and each number is unique within the financial year.
The rule requires uniqueness for a financial year, so the usual practice is to restart the running number each 1 April with the year built into the prefix. Carrying an unbroken sequence across years is not itself prohibited, but restarting keeps the year identifiable and avoids duplicates — confirm your approach with your GST practitioner.