California transparent surcharging policy
The attached code is from a law that California passed in 1985. In 2018 the law was challenged and a federal court ruled that the law could not be enforced. The wording from the court was that "This statute prohibits retailers from imposing a surcharge on customers who make payments with credit cards, but permits discounts for payments by cash or other means. The district court granted summary judgment in favor of plaintiffs, declared the statute both an unconstitutional restriction of speech and unconstitutionally vague, and permanently enjoined its enforcement. We hold that the statute as applied to these plaintiffs violates the First Amendment."
The District Attorney of California, as noted here, states that he will apply the decision of the federal court to other businesses in California. The big thing is that you can not mislead or hide the surcharge from customers, there needs to be visible and consistent signage in the clinics informing customers that for Credit Card payments only a surcharge will be applied.
Another law to take into consideration is SB 478. SB 478 is mainly a pricing transparency bill, not a bill to limit surcharging. The key factors to take into account with regards to SB 478 is that a.) a credit card processing fee is not a mandatory fee (as the customer has the option to not pay if they use cash or similar means) b.) the fact that there is a credit card surcharge is clearly and consistently advertised throughout the clinic and wherever you specify the prices for your services. You can find that information here.