Invoice Number Generator.
Generate sequential invoice numbers in multiple formats. YYYY-NNN, INV-YYYY-NNN, or custom prefix. Free, no signup required.
How to Use the Invoice Number Generator
Select a format, set a custom prefix if desired, choose your starting number, and generate a batch of sequential numbers. Copy all numbers to use in your invoicing system.
Best Practices for Invoice Numbering
Use a consistent format throughout your business. Include the year to avoid confusion across fiscal periods. Never reuse or skip numbers. If using multiple revenue streams, consider separate prefixes (e.g., CONS- for consulting, PROD- for products).
Frequently Asked Questions
How should invoice numbers be formatted?
There's no universal standard, but most countries require sequential numbering without gaps. Common formats include YYYY-NNN (2026-001), INV-YYYY-NNN, or NNN/YYYY. Choose a format and stick with it consistently.
Can invoice numbers have gaps?
Most tax authorities require sequential numbering without gaps. Missing numbers may trigger an audit. If you void an invoice, keep the number and mark it as cancelled rather than deleting it.
Should invoice numbers reset each year?
It depends on your preference and local regulations. Many businesses reset to 001 at the start of each fiscal year (using year-prefixed formats like 2026-001). Others use continuous numbering across years.