1. From your payment record, click Allocations.The payment allocation page shows a list of posted invoice lines with a balance above zero in your account.
2. From the Invoice Lines section, select the invoice lines that you want to allocate funds toward.You can select any number of invoice lines. Salesforce Billing displays an Amount field for each invoice line you select.
3. For each invoice line you selected, enter the amount you wish to allocate.The total amount allocated must be less than or equal to your payment’s balance.
4. Click Allocate.If you paid off an invoice line in full, Salesforce Billing removes it from the payment allocation page and updates its status to Paid. If you made a partial payment, you’ll see the invoice line on the payment allocation page with an updated balance.