How to use a card machine

To take a payment, key in the amount, press ENTER and let the customer tap their card or phone on the screen or insert the card and type their PIN; the machine shows approved and prints your receipt. The steps below are from providers' own user guides, with the menu names they use, plus fixes for the errors that stop a sale.

Steps from the Barclaycard, Elavon, takepayments, Square and SumUp guides, checked 1 November 2026.

How to work a card machine: taking a sale

1. At the ready prompt, key in the amount and press ENTER. If you make a mistake, press the yellow clear key and re-enter it.
2. The customer holds their card, phone or watch against the screen showing the contactless symbol (within 4cm), or inserts the card for chip and PIN.
3. The machine bleeps, shows approved and prints the merchant receipt. If the customer wants a copy, press the key shown at the ready prompt to print one.

Source: Barclaycard Portable card machine user guide. Button labels differ by model, so check the guide for your own terminal.

How to do a refund

On a terminal (Barclaycard steps)

1. At the ready prompt, open the transaction menu, highlight Refund and press ENTER.
2. Key in the refund amount, including any gratuity, and press ENTER.
3. Insert or swipe the customer’s card (below the contactless limit you can refund by contactless).
4. Swipe the supervisor card or enter the supervisor code. The machine connects to Barclaycard, processes the refund and prints a receipt.

Refund only onto the card used for the original purchase, never give a cash refund on a credit card transaction, and partial refunds are fine.

On an app reader

• Square: Open Transactions, select the payment, tap Issue refund, choose items or an amount, then a reason, and confirm. Refunds are possible within one year of the original transaction date, and Square says the customer can wait up to 4 to 14 working days for the money.
• SumUp: In the SumUp app or dashboard, tap the payment, select Refund transaction and enter your password; the money goes back to the card used.

Refunds are not free. Square states that the processing fees for the payment aren’t refunded back to you. On the house example, a shop taking £5,000 a month that refunds 2% of sales (our assumption) refunds £100.00 and loses £100.00 × 1.75% = £1.75 a month, £21.00 a year, in fees it already paid. Small, but it is why some shops offer an exchange first.

How to do end of day (banking)

1. At the ready prompt, press the menu key until the system menu shows, highlight Totals and press ENTER: End of Day Banking is highlighted.
2. Swipe the supervisor card or enter the supervisor PIN if asked.
3. Confirm End-of-Day Banking, then bank all card types at once or each acquirer (for example Amex, Barclaycard) separately.
4. The machine dials out and prints an end of day banking report for your records.

End of day banking submits the day’s payments for settlement; the money is then paid into your bank account on the schedule agreed when you signed up.

Need to check what went through? Function 16 prints a log of the last 20 transactions per acquirer (up to 100 by pressing continue), showing which were completed, cancelled or declined. On Elavon's Ingenico terminals, a stuck batch has its own fix: for a Please retry batch message, press the function key, choose BATCH, then End of Day, and confirm the totals twice.

Pre-authorisation

Pre-authorisation holds an amount on the customer's card (hotels, car hire, tabs) and completes it later. It is a feature your provider has to switch on and not every terminal supports it: Elavon lists its Ingenico DX8000 as enabled for pre-authorisation. If you need it, ask your provider to confirm it in writing before you sign.

How to reset a card machine

• Ingenico (Desk, Move and similar): Press the YELLOW key and the dot key (next to 0) together for a few seconds.
• If the machine has been unplugged for a while, reconnecting the power reboots it.
• Poynt: Press the power button at the back left of the device and choose REBOOT.
• App readers (SumUp, Square, Zettle): close and reopen the app, then switch the reader off and on.

Source: Elavon rebooting and troubleshooting guide.

Card machine errors, Bad MAC included

Source: takepayments Ingenico error messages. Function numbers are for Ingenico terminals on takepayments; other providers may use different ones.

Most of these need your acquirer, not you. If the same error keeps coming back, our guide to why your card machine is not working covers the next steps, and a free statement review will tell you whether a provider with fewer outages would also cost less.

Frequently asked questions