Your GST invoice number format for the financial year must follow three simple rules: each number is unique and consecutive within the financial year (1 April to 31 March), it is no longer than 16 characters, and it starts fresh at the top of every new year. This guide shows a safe numbering format small shops can copy, why the financial year matters, and a worked example that crosses over 1 April.
If you want the full list of fields a bill must carry, start with our GST invoice format for small shops guide — this article zooms in on just the invoice number.
What the GST rules say about the invoice number format
Under the CGST Rules, a tax invoice must carry a serial number that meets a few conditions (see the rules on cbic.gov.in):
| Rule | What it means for your shop |
|---|---|
| Consecutive | Numbers run in order — 0001, 0002, 0003 — with no gaps or repeats. |
| Unique for the financial year | No two bills in the same 1 April–31 March year share a number. |
| Up to 16 characters | The whole number, including any prefix and slashes, stays within 16 characters. |
| Allowed characters | Letters, numbers, and the special characters hyphen (-) and slash (/). |
| One or multiple series | You may run more than one series (e.g. per counter), each consecutive on its own. |
There is no single official format you are forced to use. As long as your numbers tick these boxes, you can design them to suit your shop.
A safe invoice number format you can copy
The most common, trouble-free pattern is a short prefix, the financial year, and a
running count that resets to 0001 each 1 April:
INV2026-27/0001
INV2026-27/0002
INV2026-27/0003
...
Reading it left to right: INV tells you it is an invoice, 2026-27 is the financial
year, and 0001 is the running number. Putting the financial year inside the number is
the trick that keeps everything unique — even after you reset the count, INV2026-27/0001
can never collide with INV2027-28/0001.
Count the characters and you will see this sits comfortably under the 16-character limit. Keep the prefix short so you never run over it.
Why the financial year matters
India’s financial year runs 1 April to 31 March, not January to December. Your invoice numbering follows the same calendar:
- On 31 March you issue your last bill of the year — say
INV2025-26/0742. - On 1 April the count starts again at
INV2026-27/0001.
Resetting is not strictly compulsory — what the law requires is that numbers stay unique
and consecutive within each financial year. But resetting to 0001 with the year built
into the number is the cleanest way to satisfy that, and it makes your books easy to read
at return-filing time. It also keeps the running number small and readable instead of
climbing into five or six digits over the years.
Multiple series: counters, branches, or bill types
Busy shops sometimes want more than one series — for example a separate run for the front counter and the wholesale desk, or for sales and credit notes. The rules allow this. Just give each series its own prefix and keep it consecutive on its own:
FC2026-27/0001 (front counter)
WS2026-27/0001 (wholesale desk)
Both series reset on 1 April, both stay unique for the year, and the prefix tells them apart at a glance.
A worked example across 1 April
Meena runs a stationery shop in Jaipur, Rajasthan. Here is how her numbering rolls over the year:
- 31/03/2026 — her final bill of FY 2025-26 is
INV2025-26/0742. - 01/04/2026 — her first bill of the new year is
INV2026-27/0001.
That first bill of FY 2026-27 is a walk-in sale of a ₹500 item taxed at 18%. Because the buyer is in Rajasthan too, it is an intra-state sale, so the 18% splits into CGST and SGST:
- Taxable value: ₹500
- CGST 9%: ₹45
- SGST 9%: ₹45
- Invoice total: ₹500 + ₹45 + ₹45 = ₹590
The tax split depends on the place of supply — see
CGST, SGST and IGST explained if that part is new to
you. The point here is the number: a clean reset to 0001 on 1 April, with the
financial year baked in so nothing clashes.
Common numbering mistakes to avoid
- Skipping or repeating numbers. Gaps and duplicates cause reconciliation headaches at return time. Keep the series strictly consecutive.
- Forgetting to reset in April. If you carry last year’s count forward without the year in the number, tracking gets messy fast.
- Going over 16 characters. Long prefixes plus the year plus the count can overflow — keep the prefix short.
- Editing an old bill’s number. Once a number is issued, leave it. Correct mistakes with a credit note or revised document, not by renumbering.
Let the software handle it
Getting the numbering right by hand is easy to describe and easy to slip up on — one missed reset in April, one duplicated number on a busy day, and your books stop tallying.
Yojika is offline-first GST billing software for Indian small shops. It tracks the current financial year and the last invoice number for you, increments them safely on every bill, and resets the series automatically on 1 April — so your numbering stays unique and consecutive without you thinking about it. Your data stays on your own PC.
- See what’s included on the features page.
- Or download Yojika and try it free for 14 days.
This article is general information, not tax advice. GST rules and thresholds change — confirm the current position on gst.gov.in or with your CA.