Can I issue a new invoice with an earlier date?

Yes, for work done earlier that was never invoiced. Enter the earlier date as the invoice date: the system sends it to ZATCA as the supply date, while the issue date is the actual moment of saving (the only one ZATCA accepts). ZATCA accepts the invoice that way.

Notes for the accountant:

• Saudi rules require issuing the invoice within 15 days after the end of the month of supply; a later invoice is accepted, but the delay itself may be a violation.
• If that month's VAT return was already filed, it may need amending.
• Don't do this for an invoice already given to the customer (question 13).