Cards

Cards are the rail the rest of this primer assumes. When a page here says "the payment," it means a card payment unless it says otherwise, so this page states the properties the other pages take for granted.

The defining one: a card payment asks permission before it takes money. Nothing else in common use does that.

Pull, with permission

Payment rails divide into push and pull. A push payment is the payer instructing their own bank to send money out. A pull payment is the payee instructing the payer's bank to take money in.

Cards are a pull rail, which is why they need the issuer to agree in advance. That agreement is the authorization, and it is the source of nearly everything that makes cards different from ACH: you know within a second whether the money is there, and you know it before you ship.

You pay for that certainty twice. Once in fees, because a percentage of value is expensive next to a flat few cents. And once in reversibility, because the same system that protects the buyer lets them undo the payment for months afterwards. See disputes and chargebacks.

Card-present and card-not-present

This distinction runs through the whole primer — it drives the capture deadlines, the reversal deadlines, and which interchange category a transaction lands in — so it is worth stating plainly.

A card-present transaction happens with the physical card at the terminal: dipped, tapped, or swiped. The chip or the contactless exchange proves the real card was there.

A card-not-present transaction happens without it: online, over the phone, or from stored card details. Nobody can prove the card existed, only that somebody knew its numbers.

The consequence is liability. In a card-present transaction the issuer has strong evidence and generally carries the fraud loss. In a card-not-present transaction it does not, and the merchant generally does. This is why card-not-present interchange is higher, why the schemes give card-not-present transactions longer to clear, and why authentication is worth running: it moves evidence, and liability, back towards the issuer.

Two message models

Not every card transaction sends the same number of messages, and the difference decides which operations you have.

	Dual-message	Single-message
Messages	Authorization, then a separate clearing record	One message that authorizes and clears together
Typical of	Credit, and signature debit	PIN debit and many domestic debit schemes
Can you capture later?	Yes, that is the point	No — the amount is final at approval
Can you capture a different amount?	Yes, within tolerance	No
Can you void before clearing?	Yes	No, only a refund

The whole transaction lifecycle — authorize, capture, void, reverse — describes a dual-message rail. On a single-message transaction most of those states never exist, so an integration that assumes it can always capture later will fail against certain debit products. Check which model your card mix actually uses before designing around delayed capture.

Credit and debit are not one thing

They look identical at checkout and behave differently underneath.

Debit draws on money the cardholder already has, so a hold reduces a real balance a real person may need this week. Credit draws on a line the issuer extends, and an abandoned hold is an inconvenience rather than a missed rent payment. Both are reasons to release unused holds promptly, but the debit case is the one that generates angry calls. Voids, reversals, and refunds covers the operation.

Debit cards also frequently carry more than one network, and the transaction can be routed over any of them. Which one it takes changes the cost. Routing is configured by your provider rather than chosen at checkout, so it is a question to ask in a pricing conversation, not something to build.

Scheme rules travel; economics do not

The message formats, the deadlines and the dispute rights on this rail are set by the card networks and apply broadly wherever the card is accepted. That is what makes a card work abroad.

Interchange is different. It is regulated regionally, and the caps that apply to a consumer card in one market may not exist in another. A rate quoted in one country tells you very little about the same card type somewhere else. Treat interchange figures as local and current, never as general facts, and get them from your acquirer for the markets you actually trade in.

Terms introduced

• Push payment — the payer instructs their bank to send money out.
• Pull payment — the payee instructs the payer's bank to take money in. Cards are a pull rail.
• Card-present — a transaction made with the physical card at a terminal.
• Card-not-present — a transaction made online, by phone, or from stored details, where the card cannot be proven present.
• Dual-message — authorization and clearing sent as separate messages, allowing capture later and for a different amount.
• Single-message — authorization and clearing combined, fixing the amount at approval.

The card rail

0 of 4 answered

1. What does a card payment do that a bank transfer does not?

   It asks the payer's bank for permission before any money is claimed.It moves the money in real time rather than in a batch.It guarantees the merchant will be paid regardless of what happens later.It settles directly between the two banks without an intermediary.
2. Why does a card-not-present transaction cost more and get longer to clear than a card-present one?

   The card cannot be proven present, so the merchant generally carries the fraud loss.Online transactions travel through more intermediaries, each taking a fee.The issuer cannot check the balance without the physical card.Card-not-present transactions settle through a separate, slower network.
3. What makes a payment a pull rather than a push?

   The payee instructs the payer's bank to take the money, rather than the payer sending it.The money is taken in a batch rather than one transaction at a time.The payment can be reversed after the fact.The payer's balance is checked before the money moves.
4. Your integration authorizes at checkout and captures on dispatch. Which card products can break that design?

   Single-message products, where the amount is final at approval and there is no later capture.Credit cards, because the issuer extends a line rather than holding funds.Cards issued outside your own market, which clear on a different timetable.Cards carrying more than one debit network, because routing is chosen at capture.