Invoice Payment Invoices may be paid by cash, check, ACH deposit, or credit card. However, a processing surcharge is assessed for all payments made using a credit/debit card. To pay your invoice with a credit card, please contact us at 260-489-2551 to confirm the correct or revised total. Be advised, Research Laboratories, Inc utilizes the services of PayPal for all credit card payments and some business or government pay cards are unable to be processed due to restrictions beyond our control. It is not required for customers to have a PayPal account in order for us to its service.