Tap to Pay on a smartphone: where SoftPOS is enough and where it is not

The short answer

A smartphone is a good substitute for a card terminal as long as you take few payments a month, almost everything is paid contactless and no till needs to be connected. As soon as girocard with PIN, printed receipts, a till interface or more than around a hundred payments a month come into play, a dedicated terminal is usually the better choice and often the cheaper one too.

SoftPOS means an app turns the phone and its NFC chip into a card reader. Apple calls this “Tap to Pay on iPhone”, available in Germany since 25 June 2024 for iPhone Xs and later (Apple Newsroom). On Android the same principle exists under various provider names.

Limit 1: contactless only

The phone reads only what is held against it: contactless cards, smartphones, watches. Stripe lists “contactless cards” from American Express, Mastercard and Visa as well as Apple Pay, Google Pay and Samsung Pay for Tap to Pay (Stripe, accessed 26 September 2026). There is no slot for an inserted chip card and no magnetic stripe.

In day-to-day business this affects few customers, but exactly the ones you do not want to turn away at the counter: older cards without a contactless function, cards with NFC disabled, damaged antennas. Anyone who has only a phone needs a second payment method for these cases.

Limit 2: girocard and PIN

This is the German special case. girocard is the most-used card at German terminals, but not every Tap to Pay provider accepts it. The Stripe page does not mention it. The Sparkassen-Finanzgruppe launched girocard on Tap to Pay on iPhone on 3 September 2024 with the S-POS app, including PIN entry on the merchant’s iPhone (girocard, 3 September 2024). S-POS now runs on iPhone and NFC-enabled Android devices (Sparkasse Essen, accessed 26 September 2026).

The PIN is not a side issue. From 50 euros or after several contactless payments in a row the card asks for it, as described in the article on the contactless limit. If your app cannot request a PIN, it is precisely the larger payment that fails. Apple itself gives no amount limit and only states that transaction limits may apply.

What the phone costs compared with a terminal

SoftPOS offers usually drop the base fee and charge more per payment instead. For comparison, two published price structures for girocard, as of 26 September 2026: S-POS after the promotional phase at 0.79 per cent plus 10 cents per payment according to the S-POS terms page, and PAYONE Classic with a rented terminal at 0.26 per cent plus 8 cents and from 12.90 euros rental a month (PAYONE, accessed 25 September 2026). I leave out PAYONE’s 50-euro set-up fee.

Model calculation with a 20-euro ticket size, girocard only:

Payments per month	Smartphone (0.79 % + €0.10)	Rented terminal (0.26 % + €0.08 + €12.90)
40	€10.32	€18.18
100	€25.80	€26.10
300	€77.40	€52.50

The threshold lies at around 100 payments a month. At a 5-euro ticket size a payment on the phone costs 14 cents (2.8 per cent), on the rented terminal 9 cents plus rental. This is a model calculation with two price lists, not a market overview; your own contract may look different.

The savings banks offer S-POS free of charge for twelve months under the “Deutschland zahlt digital” initiative (Germany pays digitally), including per-transaction fees, up to 50,000 euros of card turnover a year (Sparkasse Essen). Still, calculate with the price from month 13, because that is when the business keeps running.

Limit 3: receipt, till, strain

The phone does not print. The receipt goes by e-mail, QR code or not at all; anyone who needs hospitality receipts or paper slips needs a printer alongside. Connecting an existing till via ZVT or O.P.I. is not the norm for pure smartphone apps. Ask before signing, otherwise you will type every amount twice.

If the app itself records items and sales, it is an electronic recording system and needs a TSE (technical security device); details are in the article on the KassenSichV (German cash register security regulation). Then there are everyday questions: does the till run on the owner’s private phone? What happens when the battery is flat at 6 pm or an iOS update slows the app down for a week?

Limit 4: the security standard is changing

SoftPOS apps need approval under standards of the PCI Security Standards Council. The current standard is called MPoC (Mobile Payments on COTS) and combines the older standards SPoC and CPoC (PCI SSC). According to the provider MyPinPad (3 August 2026), the PCI SSC will accept no new submissions under SPoC and CPoC from 31 October 2026; I was unable to retrieve a PCI SSC announcement of its own on this. For you it comes down to one question to the provider: is the app listed under MPoC?

What I advise merchants

1. Count your card payments per month. Below around 100 the phone is a serious candidate; above that, compare it against a terminal.
2. Ask in writing: girocard yes or no, PIN entry on the device yes or no.
3. Clarify how customers without a contactless card will pay.
4. Receipt and till: do you need paper, do you need an interface, does the app need a TSE?
5. Calculate with the price after the promotional phase, not the introductory offer.
6. By all means use SoftPOS as a second device: at the market stall, at customer appointments, as a backup when the terminal fails. That is what it is made for.

Which other form factor fits is covered in the article on the five terminal form factors.