# Invoice numbers — Octyn Fuel Station Help

> Set GST invoice numbers in Octyn: continue the numbering you used before, or start a new series for the next financial year.

Canonical: https://octynerp.com/help/invoice-numbers

# Invoice numbers: continue your numbering or start a new series

[Watch the video](https://www.youtube-nocookie.com/embed/RCHsuy21SrI?rel=0)

Set GST invoice numbers in Octyn: continue the numbering you used before, or start a new series for the next financial year.

Video **3 min** Updated **1 November 2026** For **Owner or accountant** Tutorial **4 of 39**

## 01 What a series is

GST needs one consecutive series per financial year. Octyn keeps one for each outlet, and separate ones for tax invoices and credit notes.

1.  Go to **Station setup → Invoice numbers** and pick the outlet.
2.  Choose **This year** or **Next year** at the top right. You can set up the current financial year and the next one.
3.  Read the two cards — **Tax invoices** and **Credit notes**. Each shows the last number issued and the next one. With nothing set, the first sale starts Octyn's format at 1, for example KHD/2627/1.

## 02 Joined in the middle of the year? Continue your numbering

If you issued invoices before Octyn, carry on from your last one so the year stays one series.

1.  On the **Tax invoices** card, choose **Continue my numbering**.
2.  Type the last invoice number you issued, exactly as printed — for example **DI/SL/26-27/53**. The card shows the next number as you type: DI/SL/26-27/54.
3.  Zero-padded numbers stay padded: **CN/26-27/0099** continues as CN/26-27/0100.
4.  Choose **Save series**. Do the same on the **Credit notes** card if you issued credit notes.

## 03 A new financial year? Start a new series

Set up next year's series before 1 April, so the first sale of the year gets the right number.

1.  Choose **Next year**, then **Start a new series** on the card.
2.  Under **Format**, keep **Octyn format** or choose **My own format**. If you used your own format this year, Octyn suggests it with the year moved on — DI/SL/26-27/ becomes DI/SL/27-28/.
3.  Enter the **First number** — **1**, or **0001** if your numbers are zero-padded — check the preview, and choose **Save series**.

## 04 The rules that keep it lawful

Octyn refuses a series that would break GST's consecutive-numbering rule.

1.  Once Octyn issues a number from a series, the card shows **In use** and the series can no longer be changed.
2.  A number can be at most 16 characters, using letters, digits, **/** and **\-**, and needs a prefix before the running number.
3.  Each outlet and document type needs its own prefix, and a series cannot restart below a number already on a sale.

**Done.** Every counter invoice and credit note now carries the right number — on the receipt, the sales list and in GSTR-1's Documents issued. [Open it in Octyn](https://app.octynerp.com/setup/invoice-series).

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