The invoice: two currencies at once
You can invoice in the customer’s currency, but UAE VAT is reported in AED. Article 69 of the VAT Decree-Law requires amounts in a foreign currency to be converted to AED at the rate approved by the Central Bank on the date of supply. A practical tax invoice therefore shows the invoice currency and, for each VAT amount, the AED equivalent.
Whether VAT applies at all depends on the service and the customer’s location. Services to overseas business customers may be zero-rated as exports if conditions are met; services to UAE customers billed in USD are still standard-rated. Currency does not change the VAT treatment, only its conversion.