Hi Heather
If you are using the function in Receivables to create an interest batch, then there is no good way to print an invoice. The best you can do is to print a statement and the interest amount will appear as a transaction.
A client recently made the same request as yours. I used Crystal Reports to produce something that looks like their invoice, and it works for them, but it is a workaround (and it requires Crystal Reports). It prompts for the date of the interest charge, and for a range of customers.
If you are interested in seeing a sample, please email me at steve@sschwartzcpa.com.
Steve