Most freelancers stop at the invoice — send it, get paid, move on to the next project. Understandable, but that final confirmation step gets skipped more often than it should, and it's worth five minutes to close the loop properly.
An invoice alone doesn't confirm payment happened
An invoice states what's owed; it doesn't prove the client actually paid it. If a client's own bookkeeping or expense system needs proof of payment, not just a request for it, an invoice alone doesn't fully satisfy that.
It closes the loop cleanly for both sides
A short receipt confirming the invoice number, amount, and payment date gives both you and the client a clean, matched record — useful if either side needs to reconcile accounts later or if a payment dispute ever comes up.
It's a small, professional touch clients notice
Sending "Payment received, thank you" with a proper receipt attached, rather than just going quiet after being paid, is a small thing that repeat clients genuinely notice and appreciate — it signals an organized, considerate way of working.
It doesn't need to be complicated
A receipt referencing the original invoice number, the amount paid, and the date is enough — there's no need to re-itemize the entire project again once it's already been fully detailed on the invoice.
Especially important for partial or installment payments
If a project is paid in stages, a receipt for each installment keeps a clear running record of what's been paid and what's still outstanding — much easier to track than relying on memory or a single lump invoice.