Sending an invoice doesn’t lock it completely — but it does change what happens when you edit it.
What’s fully locked
An invoice is completely locked once it’s paid, refunded, or cancelled. Nothing on it can be edited at that point.
What’s still editable
A draft invoice is fully editable, with no side effects. A sent, opened, or expired invoice can still be edited too — but doing so has a consequence for your client.
What happens when you edit a sent invoice
If you edit a sent, opened, or expired invoice, SimplePayment marks your client’s existing payment link as out of date and prompts you to resend the invoice, so your client always sees the current version rather than paying against stale details.
Important behavior and limitations
- There’s no separate “locked fields” list for sent invoices — the distinction is simply: paid/refunded/cancelled is locked, everything else is editable but triggers a resend.
- Your client’s original payment link stops reflecting the invoice correctly until you resend it.
- See Understanding invoice statuses for how an invoice reaches each of these states.