Yes, pursuant to a 2012 court settlement between retailers, MasterCard, Visa and nine major banks, you are permitted to impose a surcharge on patients who pay by credit card.
However, if patients pay by debit or prepaid card, no surcharge may be imposed. The option to impose a surcharge applies to all payment channels (e.g., in person, online, through the mail or via the phone).

You are permitted to apply either a brand-level surcharge or a product-level surcharge to credit cards transactions. A brand-level surcharge is one where you charge the same percent on all credit cards brands.

A product-level surcharge is one where you impose a surcharge on a particular credit card product (e.g., Classic Card, Traditional Rewards Card, Signature Card, etc.). In both circumstances, the surcharge percent is subject to a cap.

The surcharge may not exceed the “merchant discount rate,” which is the fee, expressed as a percentage of the total transaction amount; you pay for transacting on a credit card brand.

There is also an absolute maximum surcharge cap that is set at 4 percent.

It is highly recommended that you contact each credit card brand you accept to determine the maximum surcharge you are permitted to charge.