Hi
You need to follow the below steps:
1. Create Customer Sales Order (VA01)
2. Post a customer down payment request with reference to Sales Order (F-37)
3. Convert the DPR into a down payment (F-29)
4. Billing (VF01)
5. Clear Downpayment against invoice
For tax, please ensure you maintain the tax category in Customer Down Payment GL as "*" or + for output taxes
Regards
Sanil Bhandari