ZATCA documentation has mentioned how to adjust prepayment invoices against the final invoice, but nowhere has it mentioned how is a prepayment invoice is to be created.
@Firoz Section 8 of the Detailed Guideline https://zatca.gov.sa/en/E-Invoicing/Introduction/Guidelines/Documents/E-Invoicing_Detailed__Guideline.pdf describes advance payment scenario. Please note that Advance Payment Invoice is just like any regular tax invoice with only change in the Invoice Type Code that it should be 386 instead of 388.
Invoice Type Code (BT-3): An invoice that is issued at the time of receiving payment in advance must have Invoice Type Code (BT-3) as a fixed value “386”. The subsequent invoice(s) where the advance is adjusted should have Invoice Type Code “388”.