Invoice Number Generator

Generate audit-compliant, sequential invoice numbers in popular formats. Preview, customize, and copy to clipboard.

Common: INV, BILL, FAC, RE, REKENING. Leave short (2–5 chars).

Numbering best practices

  • Gapless: never skip numbers, even for cancelled invoices. Issue a credit note instead.
  • Separate series: use different prefixes for invoices (INV), credit notes (CN), proformas (PRO), and quotes (Q).
  • Annual reset: optional. Include the year in the format to keep sequences manageable.
  • Audit trail: record when you reset or change format, in case you are ever audited.

Invoice numbering FAQ

What is the best invoice numbering format?

The most common compliant format is PREFIX-YEAR-SEQUENCE (e.g., INV-2026-001). It is gapless, audit-friendly, and supports reset annually. Alternatives include YEAR-MONTH-SEQUENCE (2026-04-0001) for higher-volume businesses and DEPT/YEAR/SEQUENCE for multi-department entities.

Can I skip invoice numbers?

No. Most tax jurisdictions (including EU VAT rules and HMRC) require strictly sequential, gap-less invoice numbering within a series. Deleting an invoice requires issuing a credit note, not removing the number.

Should I reset numbering each year?

Both are acceptable if gapless within the reset window. Annual reset (INV-2026-001, then INV-2027-001) is common. Continuous numbering is simpler but produces very large numbers over time.

Do I need a separate sequence for credit notes?

Best practice in most jurisdictions: credit notes use a separate series (e.g., CN-2026-001) to keep audit trails clean. The credit note must reference the original invoice number.

Is the generated number stored anywhere?

No. The generator creates the string locally in your browser and displays it. Nothing is transmitted or stored on any server. Copy the number into your invoicing system or our PDF generator.