Free tool

Invoice Number Generator — Get Your Numbering Right

Build an invoice numbering sequence with your own prefix, year and padding, copy the next ten numbers, and learn the simple rules that keep your invoices compliant and easy to track.

Create invoice

No signup required. 100% free.

Generate your invoice numbers

Your next 10 invoice numbers

  1. INV-2026-0001
  2. INV-2026-0002
  3. INV-2026-0003
  4. INV-2026-0004
  5. INV-2026-0005
  6. INV-2026-0006
  7. INV-2026-0007
  8. INV-2026-0008
  9. INV-2026-0009
  10. INV-2026-0010
Create invoice INV-2026-0001

The generator numbers your next invoice for you: Start new turns INV-2026-0001 into INV-2026-0002.

Why Invoice Numbers Matter

Most tax authorities require them

VAT and GST rules in the EU, UK, Canada, Australia and elsewhere require a unique, sequential number on every invoice. A missing or duplicated number can mean a rejected invoice or questions in an audit.

Payments get matched faster

Clients put your invoice number on their payment. A clear, unique number lets you match a bank transfer to an invoice in seconds instead of guessing from amounts and dates.

Accounts payable expects one

Larger clients enter every invoice into their system by number. An invoice without one, or with the same number as a previous invoice, often gets sent back, which delays your payment.

Your records stay in order

Zero-padded numbers (0001, 0002) sort correctly in folders and spreadsheets, and a year in the number shows at a glance which tax year an invoice belongs to.

How to Number Your Invoices

1

Choose a format

A prefix (INV), an optional year or year and month, and a padded counter. Set them in the tool above and see your next ten numbers.

2

Start the sequence

Put the first number on your next invoice. In Invoita, click the number on the invoice and type it in.

3

Let it count up

After each download, Start new in the generator gives you the next invoice with the number already increased and your details kept.

Invoice Numbering in Invoita

Any number format you like
Start new increases the number for you
Padding kept: INV-0099 becomes INV-0100
Your business details carried over
Number printed on every template
Remove the number if you don't need it
Rename the label, e.g. Receipt # or Quote #
PDF named after the invoice number
Draft kept in your browser
With a free account: invoices listed by number
With a free account: paid and unpaid tracked
No signup needed to start

Invoice Numbering Best Practices

1

Never reuse a number

Even if an invoice is cancelled, its number stays used. Void it or issue a credit note, keep it on file, and move on to the next number.

2

Keep one sequence per business

Running separate sequences per client (ACME-001, GLOBEX-001) makes it easy to create duplicates across clients. Use one sequence and put the client's name or PO number elsewhere on the invoice.

3

Add the year if you reset yearly

INV-2026-0001 and INV-2025-0001 can never be confused. Without the year, keep counting up across years instead of restarting at 1.

4

Pad to the volume you expect

Four digits (0001) covers 9,999 invoices; three digits is enough for most small businesses per year. Changing padding later breaks sorting, so pick generously.

5

Use the number in your file names

Save each PDF as its invoice number (Invoita does this for you). Finding an invoice months later is then a search away.

Frequently Asked Questions

An invoice number is a unique reference you give each invoice so it can be identified, tracked and matched to a payment. In most countries it's a legal requirement: every invoice must carry one, and numbers must follow a sequence without duplicates.

Use a short prefix, an optional date part and a zero-padded counter, for example INV-0001, INV-2026-0001 or 2026/10-001. Padding (0001 rather than 1) keeps numbers the same length so they sort correctly in folders and spreadsheets. Pick one format and keep it.

Yes. Many businesses start at 1001 or 100 so a first client doesn't see invoice number 1. What matters is that the numbers are unique and increase in order from wherever you start.

In the EU, UK, Australia and many other places, tax rules expect a continuous, unique sequence (gaps should be explainable, for example a cancelled invoice that you keep on file). In the US there's no single federal rule, but sequential numbers are standard practice and what auditors and clients expect.

You can, as long as each number stays unique, which is why yearly sequences include the year: INV-2026-0001 never clashes with INV-2025-0001. If you don't include the year, keep counting up instead of restarting.

Don't reuse or delete the number. Issue a credit note for the incorrect invoice (or mark it void, keeping it on file) and issue a new invoice with the next number. That keeps your sequence and your records clean.

More free invoice tools

Number Your Next Invoice

Create an invoice with your number, logo and line items and download the PDF. Free, no signup.

Create invoice