How to number invoices: simple invoice number formats that work

The basic rule

Each invoice gets a unique number, and the numbers follow a sequence with no repeats. Most tax systems, including UAE VAT, expect invoice numbers to be sequential or otherwise unique.

Formats that work well

INV-2026-00001: a prefix, the year and a running number (easy to read and sort)
2026-00001: the year and a running number
00001, 00002…: a plain running number, fine for a small business
INV-DXB-00001: a prefix per branch, if you have more than one

Tips

Use leading zeros (00001) so numbers sort correctly
Never reuse a number, even for a cancelled invoice
Use a different prefix for quotations, such as QTN-2026-00001, so they are never confused with invoices
Starting a new year? You can restart the running number if the year is part of the number

What to do if you make a mistake

Do not delete the invoice or reuse its number. Cancel it, or issue a credit note against it, and make a new invoice with the next number. This keeps the sequence complete.

How Tichkuly CRM numbers for you

Tichkuly CRM numbers invoices INV-2026-00001, 00002… and quotations QTN-2026-00001… automatically, so there are no gaps and no repeats, even when your staff make invoices from their own phones.

Try it: Invoice number generator. Get a clean run of invoice numbers in your format.

Short answers

Can two invoices have the same number?

No. Each invoice number must be unique, or your records and tax returns become hard to check.

Should invoice numbers start at 1?

They can start anywhere, for example 1001, as long as they then go up in sequence without repeats.

Do quotations need numbers too?

It helps. A separate prefix such as QTN keeps them apart from invoices and makes it easy to turn the right quotation into an invoice.

How to number invoices