Record Instant Payments in SAP Business One ERP Invoices

In SAP Business One you can record the Payment Instantly in both A/R Invoice and A/P Invoice.

Here are steps to complete it:

In the Sales module you find the AR Invoice + Payment document.The Customer code field is editable and you can input any customer code:

Enter Customer in SAP Business One ERP Invoice

When adding a new A/R or A/P Invoice, or accessing a previously created A/R or A/P Invoice which is still open, Payment Means in the menu bar is activated. In addition, there is a Payment Means icon next to the document total in the form. 

It is straight forward and intuitive.

Source from SAP Blog with minor amendment