Tap to Pay Mobile Payments SDK refund issue

Questions
1

Hi,

I have made a $1 test charge using tap to pay on iPhone in our app (currently using the development entitlement for the proximity reader), the card I used was a Interac debit card. I wanted to refund this, and I know it requires the card to be present to refund, but I see there is no Tap to Pay refund support via the Mobile Payments SDK, but even when I use the Square POS app and a physical reader it fails. I get an error stating MIX_OF_ITEMIZED_AND_CUSTOM_AMOUNT

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If I try to refund the full amount ($1), I get an error saying INSUFFICIENT_REFUNDABLE_AMOUNT.

Screenshot 2026-10-01 at 4.02.38 PM
Screenshot 2026-10-01 at 4.02.38 PM1170×2532 122 KB

I subsequently connected a Terminal to the Square POS app and succeeded in refunding the payment.

Aside from these issues, can a Terminal be used to refund an Interac payment taken with Tap to Pay or a card reader via the api? Or only through the Square POS app?

Can a card reader be used to refund a card present payment (Interac) that was taken with Tap to Pay via the mobile payments sdk?

Is there a timeline of when we might be able to expect card present Tap to pay refunds via the mobile payments sdk?

3

Also, a side note, this forum has a bug, if I do not select a category it gives me a 500 error which shows a modal that says a 422 error occurred.

Screenshot from 2026-10-01 16-22-33
Screenshot from 2026-10-01 16-22-331618×608 58 KB

4

Thanks for the question.

Mobile Payment SDK currently does not offer a supported card-present Interac refund flow, and we don’t have a timeline to share for when we can make this available.

You can refund Interac payments on a Square Terminal through the Terminal API, and it doesn’t matter how the original payment was taken.

6

I did some testing and was able to refund a card present payment taken via Tap to Pay on Apple on our app using the Square POS app with the Reader if the payment was $2 CAD. $1 CAD fails to refund with the errors previously stated.

7

Could you share both payment IDs / order IDs and the approximate timestamp? I can compare the payments, their linked orders, and refund histories to investigate why the CAD $1 attempt failed.