Charging a credit card surcharge (often around 3%) is legal in the vast majority of U.S. states, provided merchants comply with strict network rules and state regulations. Surcharges are generally prohibited or restricted in certain states (such as Connecticut and Massachusetts), cannot exceed the actual cost of processing the transaction (capped typically around 4%), and require clear, conspicuous disclosure to customers at the point of sale and on receipts before the payment is finalized. Businesses must also comply with major credit card brand guidelines and notify processors in advance.