Numbering
A scheme you can keep by hand
Three invoices a month do not need software, but they do need a scheme that still makes sense next January.
Pick a shape and keep it
Month, year and a counter — 03/2026/04 — survives a gap in the sequence and makes the year obvious at a glance.
Never reuse a number
If a document is cancelled, the number stays spent. A reused number is the one thing an accountant will certainly notice.
When a sent invoice is wrong
The correction is a separate document that refers to the original by its number. Editing the original and resending it quietly is what causes two versions to exist.
Keep a list
A single sheet with number, date, buyer and amount is enough. The template does not hold it, and without it the scheme falls apart by autumn.
What is usually done with the invoice
- Merge the invoice with an itemised statement into one file
- A watermark on a draft before it is approved
- Shrink the file if product photographs went into it