Invoice Numbers and Records: What Contractors Should Keep

The customer texts you in November about a job you did in June. They want to know what they paid, and for what. If the only record is a note in your camera roll and a number you made up that day, you are reconstructing the job from memory. A plain numbering habit and a saved copy of the invoice prevent that.

Pick a number and do not reuse it

The format barely matters. INV-0001, 2026-014, or a simple running count all work. What matters is that each invoice gets the next number, and you never hand the same number to two jobs. Gaps are fine. Duplicates are not. When a customer, a bookkeeper, or you yourself searches for "1042," there should be one bill.

Do not restart at 1 every month unless you include the month in the number. "Invoice 3" in March and "Invoice 3" in August will get mixed up the first time someone forwards an old email.

Keep the invoice, not a scrap of it

• Who it was for. Name, and a phone or email, so you can tell two customers with the same first name apart.
• Where the work was. The job address, especially if you bill property managers or work at more than one site for the same person.
• What you billed. The line items, not only the total.
• What they paid, and when. A paid invoice is a different question from an open one.
• Photos you attached. The before and after shots you put on the bill are part of the record. A camera roll is not a filing system.

An invoice file is not your bookkeeping

Keeping copies of what you sent is basic. It is not a general ledger, a payroll system, or a tax return. Your accountant still needs the records they ask for. What you should be able to pull up without a search through old texts is the bill itself: number, customer, job, amount, and whether it was paid.

EZ Invoices numbers invoices for the account and keeps the document, the line items, and the payment status together. That is the copy you send the customer. It is not a replacement for your books.