You can change the wording on your invoice form.

As RandyW stated, you can change the wording on the invoice then save that invoice template with a meaningful name (Payb4). When those customers invoices are generated, change the template being used. Or use the regular template, but change the message from "Thank you for your business" to "Payment is required before lab results released." Changing the message is probably less consistent depending how many people generate the invoices.

Depending what version of Sage50 you have, you can set up reminders to display when a customer is selected in a transaction eg: "COD! Change invoice template!" I think Premium and Quantum have that availability. Check under Additional Info in the customer record.

ok thank you I will keep your response and see what we can come up with as once the invoice saying due within 30 days is emailed it's kind of hard to force them to pay faster.