Advance Payment Product in Settings

Open Purchase Settings and pick the service product used for every advance line, here it is "[adv] Advance Payment".

Create Bill from the Purchase Order

Once a purchase order is confirmed, a new Create Bill button appears in the header and opens the advance payment wizard.

Choose How to Bill

The Bill Order popup offers billable lines, billable lines with advance deducted, advance by percentage, or advance by a fixed amount; enter the amount and click Create and View Bill.

Draft Advance Bill Created

A draft Vendor Bill opens with the advance line filled in (product, account, quantity, and unit price) and the source purchase order, ready to validate and pay.

Advance Line on the Purchase Order

Back on the purchase order, the advance appears as its own line below the goods, so the team can see how much has already been billed in advance.

Deduct Advance from the Final Bill

Pick Billable lines (deduct advance payments) in the same wizard and click Create and View Bill.

Final Bill with Advance Deducted

The final Vendor Bill shows the goods line in full and the advance as a negative line, so the total matches the remaining balance owed.