Buy now, pay later splits a purchase into instalments at no interest, and the arithmetic on a single well-managed use is genuinely zero. The cost is elsewhere: the presence of the option raises what people spend per order, and the fees arrive only when a payment is missed — which makes it cheap for the disciplined and expensive for everyone else.
That is a different shape of product from a credit card, and comparing them on APR misses the mechanism entirely.
Where does the provider’s money come from?
Mostly from the merchant, and that is the thing worth understanding. The retailer pays a percentage of the sale — typically higher than a card processing fee — because the option demonstrably increases both conversion and average order value.
The remainder comes from late fees on the minority who miss payments. Neither revenue stream requires charging you interest, which is how the "0 per cent" claim is both true and beside the point.
The AOV article covers why raising average order value is the cheapest lever a retailer has — and this is a product built to pull it.
What does splitting a payment change?
How large the purchase feels. Four payments of 50 reads as a smaller commitment than 200, and the effect is well documented across pricing research: the same amount presented in instalments produces higher willingness to pay.
It also changes what is affordable in the moment rather than what is affordable overall. Three concurrent plans of 50 a fortnight is 150 a fortnight, and none of the three showed that figure at the point of purchase.
That stacking is the specific failure mode. A single plan is easy to track; four running simultaneously across different providers with different dates is not, and missed payments are usually an administration failure rather than an inability to pay.
What do the fees look like when they land?
Flat rather than proportional, which makes them brutal on small purchases.
| Purchase | Typical late fee | As an implied rate |
|---|---|---|
| 200 over 6 weeks | ~6–12 | Modest |
| 40 over 6 weeks | ~6–12 | Very high |
A flat fee on a small balance is an enormous effective rate, in exactly the way the marketplace fee article describes for fixed transaction fees. The product is least suited to the small purchases it is most often used for.
Does it affect a credit file?
Increasingly, and inconsistently. Reporting practices differ by provider and by country, and they have been changing — some plans now appear on credit files, some do not, and missed payments are more likely to be reported than successful ones.
The asymmetry matters. A product where good behaviour is invisible and bad behaviour is recorded cannot build a credit history and can damage one, which is the opposite of how a credit card behaves.
The credit score article covers what a missed payment costs once it lands on a file, and the answer is years.
How does it compare with a store card?
Favourably on the headline and not always in substance. A store card typically offers an introductory discount and then a high ongoing rate, which is a transparent trade; the instalment plan offers no discount and no rate, which is a less legible one.
The meaningful difference is what happens after the promotional period. A store card balance that survives the interest-free window starts accruing at a rate near the top of the market. An instalment plan simply ends, which is genuinely the safer default for anyone who does not track the dates.
When is it genuinely the right tool?
When the alternative is worse and the discipline is real. Spreading a necessary purchase over six weeks at no cost is better than putting it on a card at 22.9 per cent, and better than not having the thing.
Three conditions make it work: the purchase would have happened anyway, the payments are automated, and there is only one plan running. Break any of the three and the product starts working on you rather than for you.
The simplest defence is to check the total of all active plans against a single month’s essential spending. If that ratio is uncomfortable, the number of plans is the problem rather than any individual one.
Questions people ask
Is it really interest-free? For the standard short plans, yes. Longer-term financing offered by the same providers frequently is not, and the distinction is easy to miss at checkout.
Does it count as debt? Yes, in every sense that matters — it is money owed on a schedule. Whether a lender sees it depends on the reporting, which is not the same question.
What happens if I return the item? The plan should be cancelled or adjusted, and the gap between the return and the refund reaching the provider is where payments continue to be taken. It is worth watching rather than assuming.
Is a card better? A card paid in full each month is cheaper, builds history, and carries stronger purchase protection in many jurisdictions. A card carrying a balance is considerably worse.
Zero interest is a true claim about a product whose cost is somewhere else. The budget calculator is where the stacked instalments should show up, the credit card payoff calculator is the comparison, and the discount stack calculator covers the other place a checkout percentage does not mean what it appears to.