USCIS Guidance on Payment of N-400 Application Fee with a Credit Card
You may pay for your N-400, Application for Naturalization, using a credit card. There is no additional fee to pay with your credit card. The N-400 is the only form that can be paid for by credit card using the G-1450, Authorization for Credit Card Transaction.
Acceptable Credit Cards
You may use Visa, MasterCard, American Express and Discover. You may also use gift cards with Visa, MasterCard, American Express and Discover logos.
I work in the HR department at an IT consulting firm. We needed to get an employee on board to begin a project, but first needed to transfer his visa. Dan and Anna helped make the process extremely smooth, not to mention quick. It was a pleasure to work with both of them.