As we mentioned earlier in the article, giving a number to your invoice is a legal requirement. Having a logical numbering system is crucial to managing your invoices more easily.
Here are the rules to follow:
Each invoice must have its unique identification number: there can be no duplicates.
- This number must be part of an uninterrupted chronological sequence.
In other words, your invoices must follow each other. How you choose to number your invoices is up to you, as long as the numbering system you pick is logical. For instance, nothing forces you to start your invoice numbers with 1,2,3, and 4.
Adding a prefix to your invoice numbers is also a good call, especially to help you tell your quotes and invoices apart (since your quotes, too, must have unique identification numbers). For example, use INV for invoices and QUO for your quotes.
Here are a few possible numbering sequences:
- INV001 / INV002 / INV003
- Go with a “year + number” logic: INV2022-01/INV2022-02/INV2022-03
- Use a “year + month + number” system: INV2022-01-01/INV2022-01-02/INV2022-02-03.
When using billing software, your invoice numbers will be automatically generated and follow a logical sequence without breaks. Another area you don’t have to worry about.