Guide · Invoices
How to number your invoices
Invoice numbers are boring until a customer, a bank or your accountant asks about one. Pick a system once and never think about it again.
Use one running sequence that only goes up, with a short prefix and zero padding: INV-0001, INV-0002, INV-0003. Never reuse a number. If you cancel an invoice, mark it void and keep it; don't delete it and hand its number to the next job. Number estimates on their own sequence (EST-0001) so you can tell the two apart at a glance.
Three systems that work
| System | Example | Good for |
|---|---|---|
| Simple sequence | INV-0001, INV-0002 | Most solo contractors. Easy to read out on the phone. |
| Year + sequence | 2026-001, 2026-002 | Seeing at a glance which year a job was. Restart the count each January. |
| Customer + sequence | SMITH-01, SMITH-02 | A few repeat customers. Gets messy past a dozen. |
Rules that keep it clean
- Never reuse a number. Two invoices with the same number is how payments get applied to the wrong job.
- Don't delete; void. A gap in the sequence raises questions. A voided invoice answers them.
- Pad with zeros. INV-0009 and INV-0010 sort in the right order; INV-9 and INV-10 don't always.
- Put the number on the payment. Ask customers to write it on checks and in bank transfer notes. Card payments through a pay link carry it for you.
- Keep estimates separate. An estimate isn't a bill. Its own prefix stops a customer from paying the estimate by mistake. See estimate vs invoice.
Is starting at 0001 a problem?
Some contractors start at a higher number so a new business doesn't look new. It's a style choice; nothing requires a sequence to start at 1. What matters is that it only goes up.
In Settle
Settle numbers documents for you: estimates as EST-0001, EST-0002 and invoices as INV-0001, INV-0002. When you turn an approved estimate into an invoice, the invoice gets the next invoice number. The number prints on the PDF and on the page your customer opens.
What is a good invoice number format?
A short prefix and a padded running number, like INV-0001. It's easy to read, sorts correctly and never needs explaining.
Can I reuse an invoice number?
No. Each invoice should have its own number. If an invoice is cancelled, mark it void and keep it.
Should estimates and invoices share numbers?
They can, but separate sequences (EST and INV) make it obvious which one a customer is looking at.
Settle numbers every estimate and invoice for you.
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