Is a U.S. doctor allowed to charge a client with insurance more than a client without insurance? I was told the cost for my visit was $40 if no insurance but $60 co-pay if I have insurance. I called my insurance but was told to ask a lawyer.
In the US, people are generally allowed to charge arbitrary amounts for services, as long as they do not violate various anti-discrimination laws in doing for. For example it would be illegal to charge people of one race less than they charge people of another race, because of federal and state anti-discrimination laws. Three primary factors govern the legality of a particular form of discrimination. One is the type of interaction, for example "voting rights", "public accommodation", "employment", "housing" – medical treatment would generally fall under "public accommodation". The second is jurisdiction – there can be federal, state, and municipal laws governing a particular kind of discrimination (the lower in the hierarchy you go, the stricter the laws tend to be). Finally there is the "protected class", that is, the basis for discrimination. Protected class is extremely variable, given the preceding two factors. Age discrimination is legal in ways that race discrimination is not.
"Has insurance" is not a protected class anywhere, so this does not violate any discrimination laws (per se). There are numerous legal forms of discrimination which are analogous, for example to shop at Costco at all, you have to be a member; there are numerous businesses that offer "member discounts"; some doctors work on a "subscription" basis where they don't treat you unless you are a (paid) service subscriber. The idea that a service has to treat all comers identically is legally incorrect.
Co-pay rates are dictated by insurance companies, and can vary depending on the specific insurance carrier that you have. To the extent that there are no specific laws saying otherwise, a service provider is legally entitled to charge less to a person who does not make a claims for coverage by medical insurance – or they could charge more. Indeed, the "without insurance" cost of medical services is typically higher, and the insurance company insists on doctors accepting lower compensation. A "practical" but somewhat risky solution is that if you know that the copay is higher than the street price, you can simply not reveal that you have insurance. However, sometimes an office visit results in a finding that some treatment is needed, and the street price for that treatment may be substantially higher than the insured price. At any rate, contractually-determined co-pays are legal.
I should mention a remote possibility for applying anti-discrimination laws, owing to sec. 1557 of ACA. See this article on health care discrimination litigation, where the law enabled "private right of action for disparate impact claims opens the door to class-based claims challenging facially neutral health care policies, treatment decisions, and insurance coverage on the basis that they disproportionately affect members of protected classes". Under this regime, if a policy effectively discriminates on the basis of a protected class, without explicitly mentioning the class, the policy could still be found illegal. If there is a strong enough correlation between race and having health insurance, then "having health insurance" could be found to be a substitute for discrimination on prohibited grounds. There isn't enough case law on this issue, that we can clearly say that such an argument would or would not work.
Some insurance companies negotiate a "most favored nation" clause in their contract with providers that requires in network providers to share the insurance company's insured the lowest rate it charges others. But, that is purely a matter of the contract between the insurance company and the provider of which the insured is a third party beneficiary.
Normally, there is no contract of this type between an insurance company and a non-network provider. And, even when a contract between an insurance company and a provider does have a "most favor nation" clause, the exact details of that requirement vary.
There is no statute or common law rule that prevents providers from charging more to uninsured patients than to insured patients in most of the U.S., although it is possible that some U.S. state may have such a law.