Any business that accepts, processes, or stores payment card data is expected to meet PCI DSS, the Payment Card Industry Data Security Standard. It is not a government law but a requirement imposed by the card networks, and failing to meet it can mean fines, higher fees, or losing the ability to accept cards at all.
PCI DSS sets a broad set of security requirements around cardholder data: protecting stored data, encrypting it in transit, restricting access on a need-to-know basis, maintaining secure systems and networks, monitoring and testing, and keeping a formal security policy. The level of validation required scales with how many transactions a business handles.
The most important practical insight is that the burden depends on how much card data you touch. A business that stores card numbers takes on the full weight of protecting them. A business that never lets card data hit its own systems, by using tokenization and a compliant payment processor so the sensitive data goes straight to the processor, dramatically shrinks its PCI scope and its risk. Designing payments to minimize scope is the single biggest lever.
For most businesses, the smart path is architectural: use compliant payment infrastructure so card data never rests in your environment, then validate the reduced scope that remains. Building software this way, keeping the sensitive data out of reach by design, is far cheaper and safer than securing data you did not need to hold.
The best card data is the data you never hold.
This is general educational information, not specific security, compliance, or legal advice for your systems.