Clear rules and traceable stamps are your best starting point for stamp card fraud prevention. These six cases show where to focus so rewards reach the customers who earn them.
1. The bought stamp
Paper card stamps with cups, hearts or stars cost a few euros online. Someone who knows your design can often buy a similar one and fill their card at home.
How to spot it: Cards that fill up suspiciously fast. Fields where the ink looks slightly different. Stamps that all sit perfectly straight, when your team tends to stamp at an angle during the rush.
What helps: Use a custom logo stamp instead of a stock design. Initials or dates in each field help, but are hard to maintain during a rush. An unusual hole punch is harder to buy. With digital cards, there is no stamp to copy this way.
2. The favour on the team
One possible loophole starts with staff: two stamps for a flatmate or a full card for friends who bought nothing. Usually the intention is to be kind.
How to spot it: Paper rarely gives you a record to check. With digital cards, the log can help: one team member hands out noticeably more stamps per shift than the others, or individual cards get several stamps in quick succession.
What helps: Set a clear rule with some allowed discretion. Say it aloud: one purchase, one stamp. You might allow one card per shift an extra stamp, for a customer having a bad day or a child with their first hot chocolate. Make these gestures an explicit part of the policy so staff know what is allowed.
Give each person their own login so you can trace stamps. A shared password makes the log useless. Individual logins and roles are on every plan. The log with time, location and person comes with the Start plan at €7.99 a month (incl. VAT). On Start and up, admins and managers can correct the count in a customer’s profile using “Stempel anpassen” (adjust stamps).
3. The photographed QR code
In some poorly designed digital systems, scanning the stand’s QR code adds a stamp. A photo can then let someone keep stamping from their sofa.
How to spot it: Stamps at times when you’re closed. Cards that get a stamp every day, even though you’ve never seen the face behind them.
What helps: Use a system where staff set or confirm stamps. With Treubar, your team scans the card, or customers stamp themselves at the NFC stand. Each tap counts once; a photo cannot add stamps from the sofa. You can also enable a minimum gap between two stamps and stamp expiry in the app. From Start, the log shows stamps and redemptions with time, location and, for staff scans, the team member. The minimum gap matters most for NFC self-stamping. See the flow on the stamping by QR code page.
4. Five coffees, five stamps?
A customer buys five coffees for the office and wants five stamps. This is not fraud; you have not yet set a clear rule. Inconsistent decisions cause friction: five stamps on Monday, one on Tuesday.
What helps: Set the rule once and display it. “One visit, one stamp” usually works well: quick to explain, no negotiation. Per drink is fine too if the card says so and everyone follows it. For stamps per visit, a minimum gap can prevent a second stamp during the same visit.
5. The shared card
A couple shares a card, or three colleagues pool theirs. This may look like cheating, but every stamp represents a paid purchase. Ten purchases earn the same reward and cost you the same, whether one or two people made them.
What helps: Usually no action is needed. With one stamp per purchase, sharing creates no loophole. Confronting customers risks more than a coffee.
Paper has one exception: someone who collects other people’s lost or abandoned cards and combines them is redeeming rewards that others paid for. A wallet card lives on its owner’s phone and can’t be collected like that.
6. The card from the drawer
Three years after the last stamp, a full card returns. The reward no longer exists in that form or the shop has changed owners. It is not fraud, but it makes for an awkward moment.
What helps: Display expiry terms from day one, in the small print on paper cards. Do not add them later. Treubar can expire stamps after a period you choose without a new stamp. The card warns customers 30 days before. Unlocked rewards remain. Choose a generous period that fits visit frequency. Work out the time needed with how many stamps should your card have?
Check unusual patterns and keep service friendly
Review stamps issued in quick succession or outside opening hours. An unusual entry is a reason to ask a question, not proof of fraud. Different shifts and duties can also explain different stamp totals.
Tell your team what you use the log for. If your German business has a works council, respect its co-determination rights when introducing and using the system (§ 87 (1) no. 6 BetrVG). See stamp cards and GDPR for handling guest data.
For a practical look at rewards and running costs, read is a stamp card worth it?.
Frequently asked questions
What do I say if I notice a fake stamp?
Stay calm and avoid accusations: “I’m not sure about these two fields, so I can’t count those, sorry. The others, absolutely.” If you are switching to digital anyway, transfer the genuine count and leave it there.
Can a digital stamp card be faked?
It is harder than with paper. The system issues the wallet pass and keeps the count. An edited screenshot cannot change it: stamps and redemptions happen by scan. Weaknesses are more often in flows without staff checks; see point 3.
Is it worth the effort for such small amounts?
Rarely for one-offs, but yes for repeated loopholes. Extra stamps every shift cost more over a year than an occasional forgery. Individual logins and a weekly look at the log are more useful than counter checks.
Should I tie stamps to a minimum spend?
Usually not. Minimum spends add arithmetic and debates at the till. Clear stamping rules and a minimum gap prevent abuse more effectively. Find more answers in the FAQ.
Start with clear rules and digital stamps
With Treubar, your team stamps by scanning and uses individual logins. Start free with up to 20 customer passes, or choose Start for the stamp log and customer list.