The bill number is not decoration. It is how your accountant finds the document, and it has to continue the series you have always used.
A business changing software mid-year cannot restart its invoice numbers at one. The series has to continue, the prefix has to stay recognisable, and quotations must not share a sequence with invoices or the filing falls apart.
Setting the prefix and the running number per document type keeps the books continuous across the switch, and keeps each kind of document identifiable at a glance afterwards.
Whatever your books already use.
Continue from where your last bill left off.
Quotations and invoices need not share a series.
Every document takes the next number in its own sequence.
The parts that make the app yours: your numbering series, your terms at the bottom of the bill, your branding, more than one firm under one account, and a way to bring existing data in from a spreadsheet instead of typing it.
This is setup work — done in the first week, and then again whenever the business adds a firm, changes a series or closes a year.
The other things that make a bill yours.
Yes — set the prefix and the next number so the series carries on rather than restarting.
They need not. Each document type can run on its own.
Yes, where you run more than one firm each keeps its own series.
Switching software should not restart your invoice numbers at one.
