Card Controls

Card controls are restrictions attached to a payment card that determine which transactions will be approved. They can limit the amount that may be spent, the kinds of merchant where the card works, the channels through which it can be used, the countries in which it is accepted and the times at which it is active. The cardholder, an account administrator or the issuer sets the rules, and the issuer's systems check them whenever the card is presented.

Controls serve two purposes. For consumers they are a security and budgeting tool, offered through banking apps. For businesses they are the core of expense management, where they are more often called spend controls: a company gives staff cards that can be used only for approved purposes. Modern issuing platforms expose controls through programming interfaces, so that a fintech programme can define them per card.

• Amount limits. A spending limit caps the value of a single transaction or the total over a day, week, month or the life of the card.
• Frequency limits. A velocity limit caps the number of transactions in a period.
• Merchant restrictions. Rules based on the merchant category code allow or deny whole classes of business, for example permitting fuel and blocking gambling. This is known as MCC blocking. Some platforms can also lock a card to a single named merchant.
• Channel restrictions. The card can be switched off for online purchases, for contactless use, for magnetic stripe transactions or for withdrawals at an ATM.
• Geographic restrictions. Use can be limited to certain countries or blocked abroad.
• Time and validity. A card can be valid only between set dates, or only during working hours.
• On and off. A card freeze suspends all use until the holder lifts it.

Controls act at the moment of payment authorization. When the card is used, the merchant's request travels through the card network to the issuer's issuer processor. Before checking the balance or credit line, the processor compares the request with the card's rules: the amount, the merchant category, the country, the entry mode and the running totals. If any rule is broken, the request is declined with a code indicating a restriction.

Some issuing platforms go further and pass each request to the programme's own systems for a decision in real time, a design called real-time authorization. Combined with just-in-time funding, this lets a programme apply any logic it likes, such as approving a purchase only if it matches an open purchase order, and moving funds to the card only when the purchase is approved.

Banks and card issuers offer controls in their apps as a response to fraud and as a convenience. A customer who rarely shops online may switch off remote purchases; a traveller may enable foreign use only for the length of a trip; a parent may cap what a teenager's card can spend and where. Several banks offer a gambling block, which declines transactions at betting merchants and applies a waiting period before it can be removed. Alerts for each transaction often sit beside the controls and serve a similar protective purpose.

In business programmes, controls replace after-the-fact policing of expense claims. A corporate card can be limited to travel merchants, a fuel card to filling stations, and a purchasing card to approved supplier categories. Controls are tightest on virtual cards. A single-use card can be created for one supplier invoice, with a limit equal to the invoice amount and a short validity period, so that the number is useless if it is intercepted. Travel agencies, insurers and accounts payable departments use this approach at scale, and subscription management tools issue a separate card per vendor so that one can be cancelled without affecting the others.

Controls can only act on information present in the authorization message, and that information is imperfect. Merchant category codes are assigned by acquirers and are sometimes wrong or too broad: a supermarket that sells fuel, or a marketplace selling many kinds of goods, carries a single code. A blocked merchant may trade under a different code through an intermediary.

Some transactions bypass real-time checks. An offline authorization, as on some aircraft or transit systems, is approved by the terminal without contacting the issuer. Clearing amounts can differ from authorized amounts at hotels, fuel pumps and restaurants, where tips or final charges are added later. Under card network rules a merchant can also submit certain transactions without a fresh authorization, and these may be posted even if a control would have declined them.

Frozen or restricted cards can still be charged in some circumstances, for example where a recurring payment has already been authorized or a refund is due. Controls reduce exposure to card fraud and misuse, but they do not replace monitoring of statements or the cardholder's dispute rights.