By now every method of invoice numbering has probably been tried.
However, this one is the best.
There are dozens of ways to number invoices. Complex ways. Simple ways. Informational ways.
Information about the particular invoice
Information about the next invoice number to use
Recognition that computers handle alpha-numeric stuff really well
A scheme that makes it easy to know what the current invoice number should be; and a scheme that also conveys more information months later than a sequential number can do.
The ideal scheme needs a project identifier and a sequence number.
What is the project identifier?
A Project ID. Think of this as a stock market ticker tape symbol or an airport designation. It is a few letters and maybe numbers that will tell you exactly what project you are referencing. If you don’t do a lot of projects for each client, then you can use their name for the ID. If another project eventually materializes for this client, add a “2”. E.g. CNNR, then CNNR2. CNNR stands for The Connor House.
If you do multiple projects for clients, use a combination of CLIENT-PROJECT for the Project ID. Say IP-WIL for the International Paper Wilmington Distribution Center. Or this same project could have the identifier of IP.WDC.
The key issue is to create an ID that tells YOU what project this is.
Some ways to go:
What about the number part of the invoice?
You will know what number this new invoice gets without any research. It is in sequence for the project. Later you know what timeframe this invoice is referencing. Because of the Project ID it, an invoice number is still unique even though several invoices make use of this same number.
So the recommended invoice numbering scheme is to use a combination of a ‘Project ID’ and a date-based number. For example, MHA-1911, which would stand for the Meyer House Addition invoice for work during November of 2019.
Tells you exactly what the invoice is for
You don’t need to look up the last (or any) invoice to know what this invoice number should be
Not very mysterious