Pick a format, choose your starting number, and preview your sequence.
Your next 8 invoice numbers:
Orange = your next invoice number
INV-001INV-002INV-003INV-prefix
Most common. Clean, universal, recognisable.
2026-0012026-0022026-003Year + sequence
Makes the year visible. Good for tax filing.
2026-INV-0012026-INV-0022026-INV-003Year + INV
Combines both. Used by larger freelancers.
ACME-001ACME-002ACME-003Client-prefixed
Per-client sequences. Good for retainers.
Sequential
Invoice numbers must be sequential β no gaps, no duplicates. Skipping from INV-003 to INV-007 can raise red flags during tax audits.
Unique per business
Two invoices must never have the same number. Reset per year (2026-001) only if your system makes it obvious (e.g., year-prefixed).
No meaning required
Your invoice numbers don't need to encode any information (client name, date, amount). Sequential integers are fine.
Tax authority expectations
Most EU/UK tax authorities expect sequential numbering with no gaps. The Netherlands (Belastingdienst) and HMRC both audit this.
Once sent, don't change it
If you send INV-042 and need to correct it, issue a credit note and send INV-043 (corrected). Never edit a sent invoice's number.
Do invoice numbers have to start at 1?
No β you can start at any number. Many freelancers start at 100 or 1000 so early invoices don't look like they're from a brand-new business.
Can I reset numbering each year?
Yes, if your format makes the year explicit (e.g., 2026-001). Don't reset a plain INV-001 sequence mid-year or you'll have duplicate numbers.
What if I skip a number?
Issue a void/cancellation notice for the skipped number and note it in your records. This satisfies tax authority requirements in most countries.
Does the format matter for VAT?
The format is up to you, but the number must be unique and sequential. Some countries require the invoice number to appear on VAT returns β make sure yours is clear.
Auto-number your invoices with Chaser
Chaser auto-assigns sequential invoice numbers (INV-001, INV-002...) and chases late payments automatically. Never chase invoices manually again.
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