Just need some advice on a system of invoice numbers. I started a small business and I need to create invoice numbers for my customers. Is there any science or system behind invoice numbers ??? How can they be coded so you can store built-in information ??? FYI – I have a small construction contractor business.

1. Add a prefix to indicate the invoice.
It’s better to add a prefix for invoice, like INV. This can help you to organize different types of documents, like quotation, invoice, receipt, etc.
INV – Invoice
REC – Receipt.

2. Dont make it too long.
It is troublesome if you or your customer want to reference it.

3. Add Time field.
You may add the Year or Month into, for example INV200908 or INV081234. You can easily track the invoice accordingly.

4. Start it from somewhere and not 1.
It gives a good impression to your customer.
It is really odd if your invoice number is INV00001.

5. Add Category field.
If you have different types of services/products, you want to differentiate it out in the number.
You can add a suffix. For example, add "C" to represent the consultation job.

So, you may come up with something like this
INV200908501, INV200908502, INV200908503

In next month, you have
INV200909501, INV200909502, INV200909503