If you used Apple Pay to pay for something in-store but then decide that you need to return it, the process in most cases is just as easy as purchasing the item in the first place. In most cases, you won't even need anything but your iPhone that's set up with Apple Pay and your thumb print.
How to get refunded for an in-store Apple Pay purchase
Give the merchant your receipt and tell them what items you'd like to return. They can start processing it just like any other return.
When asked, go ahead and tap your iPhone just as you did to pay and verify the return with Touch ID.
Alternately you can also give the cashier your Device Account Number so they can look up the transaction that way if they need to.
Launch Passbook on your iPhone and choose the card you originally paid with.
Tap on the info button in the lower right hand corner.
Give the cashier the last four digits of the Device Account Number — it's towards the bottom.
Keep in mind that some merchants may require an ID in order to process a return, especially if it's a higher dollar transaction. So bring that with you too, just as you would with any regular credit card purchase.
That's it! In most instances, a return should work with Apple Pay the same as it would if you had swiped a regular card. The only difference is that instead of the merchant having to swipe your card again in order to put money back on (some merchants don't even have to do this anymore), you'll just have to tap your iPhone on the payment terminal again and verify the return. Just be sure to check with your merchant on how long it'll take in order for the refund to actually show up on your credit card.