Never skip an invoice number — even for cancelled invoices
Tax authorities in many jurisdictions require sequential invoice numbers with no gaps as evidence that all invoiced amounts have been properly declared. If you issue INV-001 and INV-003 with no INV-002, auditors will ask what happened to the missing invoice. If you cancel an invoice, issue a credit note referencing the original invoice number rather than reusing or skipping the number. The original invoice should be kept in records marked as cancelled.
Include the client name in your file naming, not the invoice number alone
For your own record-keeping, name invoice files with both the number and client: INV-2024-042-AcmeCorp.pdf. The invoice number alone does not tell you who the invoice is for when scanning a folder. The client name alone does not give you the date and sequence context. Both together create a perfect file name that sorts correctly and is immediately informative.
Reset your counter at the start of each year
If your invoices include the year in their number (INV-2024-001), reset your counter to 001 at the start of each year. Enable the "Auto-reset counter on new year" option in the tool to handle this automatically. The year in the number means each year's invoices have their own sequence, making it easy to see at a glance how many invoices were issued in any given year.
Use 3-digit padding unless you issue more than 999 invoices per year
Three-digit padding (001–999) is sufficient for most freelancers and small businesses. If you typically issue fewer than 100 invoices per year, even 2 digits would suffice, but 3 is the professional convention. If you issue more than 999 invoices per year, use 4-digit padding. The generator supports up to 5-digit padding for high-volume invoicers.
Add your company code as a prefix for multi-entity businesses
If you operate multiple business entities, brands, or projects, use a distinct prefix for each: BRAND1-2024-001, BRAND2-2024-001. This prevents confusion when clients from different brands receive invoices and makes bank reconciliation much easier. The generator lets you set any prefix — use your company abbreviation, project code, or client code for client-specific sequences.