How invoice numbering works
Setting up invoice numbering in Xero and what to do if you spot a gap
Every invoice you raise must have a unique sequential number. This is a legal requirement for VAT-registered businesses and good practice for all companies.
Setting up invoice numbering in Xero
Xero assigns invoice numbers automatically in sequence starting from whatever number you set. During setup, we configure the starting number (for example INV-001 or INV-2025-001). Xero increments it automatically for every new invoice. Never change the numbering system mid-year as gaps or duplicates in the sequence may attract HMRC scrutiny.
What to do if you spot a gap
If you notice a gap in your invoice sequence (you went from INV-042 to INV-044 with no INV-043), investigate whether a transaction is missing from Xero or whether the gap arose from a deleted draft. Document the explanation. If you can’t identify the cause, contact us.
💡 Good to know: HMRC can request to see a complete run of invoices during a compliance check. A clean sequential run with no unexplained gaps is the best evidence that all income has been declared.
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