I can confirm that PayUSATax is to be avoided. Made a $5K payment that was rejected by the IRS (payusatax sent an email with that message). Not knowing what was going to happen next, I tried to get in touch with PayUSATax but that is completely impossible. After waiting on hold for over an hour, you get automatically disconnected. Messages and emails are completely ignored. Luckily for me, the payment was refunded automatically after about a week but I won't use them again since they ignore customers completely if something goes wrong that their computer system doesn't handle. Many negative reports online if something goes wrong.