Invoice Number Generator
Generate sequential invoice numbers with a custom prefix, date segment, separator, and zero-padding. Copy the full list or download as a .txt file — no sign-up required.
Frequently Asked Questions
What invoice numbering format is required under GST in India?
Under the GST Act, a tax invoice number must be a consecutive serial number not exceeding 16 characters, using alphanumeric characters and special characters like a hyphen or slash. Each financial year (April to March) can have its own series. A common format is PREFIX-FYYEAR-NNNN — for example, INV-2526-0001 for the first invoice in FY 2025-26. The series must be unique per GSTIN. Because B2B invoices auto-populate the buyer's GSTR-2A from your GSTR-1, consistent and unique invoice numbers are critical for GST reconciliation.
Should I reset my invoice number sequence each financial year?
Yes, most accountants and the GST portal recommend resetting your sequence at the start of each financial year on 1 April to keep audit trails clean. The simplest approach is to encode the financial year in the prefix — for example, INV-2526-0001 through INV-2526-XXXX — so each year's invoices are distinct even after the sequence resets. If your accounting software does not support automatic resets, use this tool to plan your numbering scheme before the new financial year begins.
How many digits of padding should I use for invoice numbers?
For most freelancers and small businesses issuing fewer than 1,000 invoices per year, three digits (001–999) is sufficient. If you expect to scale or want room to grow, use four digits (0001–9999). Fixed-width zero-padded numbers sort correctly as strings in your accounting software — INV-0042 sorts before INV-0100, whereas INV-42 would sort after INV-100 in a plain alphabetical sort. GST allows up to 16 characters total including the prefix, so the padding choice is mainly about readability and software compatibility.