Why does a service fee show up when submitting payment information for Federal tax payment if I was already charged $124 for federal prep with electronic filing included?

If you are paying the Federal taxes owed to the IRS, there is a fee to pay them with a credit card. This is because it is done using a third party processor.  I am including our FAQ below for more information. 

https://ttlc.intuit.com/replies/4232265