Never edit the original invoice and resend with the same number — that creates two versions of the same invoice and breaks accounting. Instead: void the original (mark as VOID, $0) OR issue a credit note that reverses it, THEN issue a new corrected invoice with a new sequential number that references the original. This guide covers when to use each option and the email templates for communicating with the client.
No — never delete. Both for legal/tax reasons and to maintain the unbroken sequential numbering required for audit defensibility.
Void if the client hasn't already entered the invoice. Credit note if they have, or if you're VAT/GST-registered.
Generally no — once paid, the transaction is closed. If you need to adjust, issue a credit note for the adjustment amount.
If they overpaid: issue a credit note for the overage. If they underpaid: issue a corrected invoice for the difference.
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