Invoice purchase and BNPL: what do Klarna, PayPal and the rest cost the merchant?

The short answer

Invoice purchase and instalments — grouped in the market under “buy now, pay later” (BNPL) — cost the merchant more than any card payment: in Mollie’s published list prices for Germany, Klarna and Riverty each sit at 2.99 per cent plus 0.35 euros, and the B2B service Billie at 3.49 per cent plus 0.35 euros (retrieved on 16 October 2026). In return the merchant gets something a card payment does not offer: the provider pays out immediately and in full and carries the default risk.

The decisive question is therefore not whether BNPL is more expensive — it is — but whether the extra sales and the offloaded defaults are worth the surcharge. That can be calculated, not guessed.

What does invoice purchase cost per basket size?

The fixed amount per payment makes BNPL disproportionately expensive on small baskets, and the percentage on large ones. Worked example using Mollie’s list prices of 16 October 2026, with an EEA consumer card (1.80 per cent plus 0.25 euros) and SEPA Direct Debit (0.35 euros fixed) alongside for comparison, both also from the Mollie list:

Basket	Klarna / Riverty (2.99 % + €0.35)	effective	EEA card (1.80 % + €0.25)	SEPA Direct Debit (€0.35 fixed)
€30	€1.25	4.16 %	€0.79	€0.35
€80	€2.74	3.43 %	€1.69	€0.35
€300	€9.32	3.11 %	€5.65	€0.35

At 300 euros, the same purchase via Billie (3.49 per cent plus 0.35 euros) costs 10.82 euros instead of 9.32 euros. Two things are certain: against direct debit, BNPL loses by a mile at every amount; against the card, by roughly a factor of 1.6 to 1.8. And the smaller the ticket, the worse the maths — below around 20 euros, invoice purchase is almost always the most expensive method at checkout.

What the higher fee pays for

A card payment costs the merchant interchange, scheme fee and the provider’s margin — I took those building blocks apart in the guide to card payment fees. With invoice purchase a fourth element is added, and it is the most expensive: taking on the default risk.

The model is the same with all the common providers. PayPal puts it this way on its merchant page: the payout to the merchant is made “immediately and in full”, and PayPal takes over “the entire handling of the instalments, including repayments and payout risk” (PayPal merchant page, retrieved on 16 October 2026). If the customer does not pay, that is no longer the merchant’s problem. It is precisely this guarantee that pushes the rate from around one per cent (card) to around three per cent (BNPL).

That is a fair trade, but only if the risk is real. A merchant with well-off regulars and low defaults is buying insurance he barely needs. A shop with high baskets, new customers and noticeable payment defaults gets real relief for the same money.

The products hiding behind BNPL

“Buy now, pay later” is not a single product but a bundle. Klarna lists four building blocks on its seller page (retrieved on 16 October 2026):

• Pay now — the customer pays straight away, effectively a normal payment.
• Invoice purchase — payment after a term, usually 30 days.
• Instalments — split into three or four instalments.
• Financing — longer-term instalment loans.

PayPal offers the same as “Später bezahlen” (pay later): pay-after-30-days for baskets of 1 to 2,000 euros and instalments of 99 to 10,000 euros, each with a credit check (PayPal merchant page, retrieved on 16 October 2026). Crucial for the calculation: for the merchant, PayPal charges no separate BNPL surcharge — the normal checkout fee applies. Anyone already accepting PayPal has “pay later” on offer essentially for free. Billie, in turn, is the special case of invoice purchase between businesses (B2B); the higher rate reflects the different risk profile.

Klarna itself publishes no fees on its seller page; the rates above come from the price list of Mollie, through which Klarna can be booked as one of several payment methods. Anyone integrating Klarna directly gets their own negotiated terms — which can be above or below these.

Invoice is not the same as direct debit

The most common fallacy: “invoice” sounds cheap because no card is involved. In fact, classic invoice purchase through a BNPL service is the most expensive variant, and SEPA Direct Debit by far the cheapest — 0.35 euros fixed, regardless of the amount. The difference is again in the risk: with direct debit the merchant carries the chargeback risk himself, and a hard one at that. The customer can claw back a core direct debit for eight weeks without giving any reason (§ 675x BGB). What that means in practice is in the guide to chargebacks with card and direct debit.

In short: the three methods differ not in convenience but in who ends up stuck with the payment default. That is the honest yardstick for the price.

May I charge a surcharge for invoice purchase?

Unlike consumer cards of the girocard, Visa and Mastercard systems and SEPA Direct Debit, for which § 270a BGB bans a surcharge in consumer business, invoice purchase does not fall under that ban. A separate fee is in principle possible here. Whether it is worth it is another question: a visible surcharge at the most expensive point of the checkout is often exactly why a customer walks away — and then the whole idea was for nothing.

What I advise merchants

1. Know your own defaults. A merchant with barely any payment defaults is paying for insurance with no claim.
2. Decide by basket size, not by feeling. Below around 20 euros, invoice purchase is almost always the most expensive method; the fixed amount sees to that.
3. Check PayPal’s „Später bezahlen“ first if PayPal is already in the checkout — it carries no separate surcharge.
4. Keep SEPA Direct Debit in mind as the cheap alternative, but price in the eight-week right of return.
5. Negotiate the terms when integrating Klarna or Riverty directly rather than accepting the list prices from an aggregator.
6. Measure the extra conversion, don’t assert it: only a before-and-after comparison shows whether BNPL earns back the three per cent.