Interchange as a growth lever: the hidden revenue most issuers leave on the table

Most card-issuing banks treat interchange revenue the same way they treat rainfall, something that shows up on a schedule you don't control, in amounts you can predict but not meaningfully influence. You count it, you budget for it, and you move on.

This is a mistake. And the banks that figure it out first will have a significant structural advantage over those that don't.

What interchange actually is, and why it's controllable

Interchange is the fee paid by the merchant's bank to the cardholder's bank every time a card transaction is processed. Rates vary by merchant category, card type, and region, but the underlying mechanic is simple: more transactions mean more interchange, and higher-value transactions mean more interchange.

Here's the part most issuers miss: interchange is not just a function of how many cards you've issued. It's a function of how actively those cards are used, at what merchants, at what frequency, and for what transaction amounts. All of those variables are behaviourally driven, which means they're influence-able.

The three interchange levers

Think about your portfolio's interchange income as the product of three separate drivers, each of which can be moved independently.

1. Active card rate. A card that doesn't transact generates zero interchange. The most direct way to grow interchange revenue is to reduce the proportion of dormant cards in your portfolio. A 10-percentage-point improvement in active card rate across a portfolio of 500,000 cards is not a minor footnote, it's a material revenue line.

2. Transaction frequency per active card. Even among active cardholders, most use their card at a narrow range of merchants and occasions. Nudging a cardholder who currently transacts 4 times per month to transact 6 times is a 50% uplift in their interchange contribution, with no change in card numbers or credit limits.

3. Spend mix and merchant category. Not all transactions are equal. Interchange rates vary by merchant category code (MCC). High-value spend categories, travel, dining, fuel, insurance, typically carry more favourable interchange economics than everyday grocery or utilities spend. A cardholder whose spend shifts toward these categories is worth more to the issuer, even at the same total spend volume.

Why this requires a behavioural approach

You cannot move any of these three levers through product changes alone. Lowering annual fees doesn't make dormant cardholders transact. Increasing credit limits doesn't change spend mix. What moves cardholder behaviour is relevance, the right message, to the right person, at the right moment.

This is where behavioural segmentation becomes commercially critical. A dormant cardholder who last transacted at a fuel merchant six months ago needs a different reactivation message than one who was using the card daily for groceries and simply stopped. A high-frequency transactor who never uses the card for dining is a different opportunity than one who eats out regularly but reaches for a competitor card.

When you treat all of these as one undifferentiated group and send a single campaign, the conversion rate is low, typically 2–4%. When you segment behaviorally and send nudges calibrated to each archetype's specific usage pattern, conversion rates of 10–15% become achievable.

The compounding effect

Here's what makes interchange optimisation particularly attractive as a strategic priority: the gains compound. A cardholder reactivated this month generates interchange for the next several years. A dormant cardholder who is never reactivated represents not just the lost interchange of their dormant period, but the accumulated cost of their acquisition, card issuance, and ongoing servicing, all unrecovered.

The present value of reactivating a single dormant card over a three-year horizon is substantially larger than the month-one interchange it generates. Bank finance teams that model this correctly tend to allocate meaningfully more to behavioural engagement programmes, because the ROI, properly calculated, is among the most attractive in the card business.

Where to start

The most pragmatic entry point is dormancy reduction. It's the highest-ROI lever, the most tractable problem, and the one where behavioural data provides the clearest signal. Which dormant cardholders transacted recently at merchants that are already in your reward network? Which ones lapsed after a specific life event, a salary change, a location change, a large purchase? These are recoverable relationships with a known trigger.

From there, frequency nudging and spend-mix optimisation become the natural next phase, layering on incremental revenue from your already-active base.