Phone

If you bought the iPhone using Apple Card Monthly Installments, the due amount for each month must be paid in full to not incur interest. If you pay less than the amount due for that month you will incur interest.

If you used some other 24 month no interest offer from your card issuer or mobile service provider, contact them directly.

click here ➜ How to make Apple Card payments - Apple Support

When your minimum payment is due, Payment Due appears with the amount below your Apple Card. If you bought an iPhone, iPad, Mac, or other eligible Apple product with Apple Card Monthly Installments, your monthly installment is included in the minimum payment amount.

Then it should show your minimum due for the month, which includes the installment, unless you did not actualy select the Monthly Installment option. It is not selected by default, and installments do not get applied if oyu select single payment during checkout.

Are you sure its asking you to pay the full amount for the iPhone?

Did you make the minimum payment?

Then I’m not sure what you are seeing. You will see the entire cost of the iPhone on the card, and your available limit will be reduced by that amount, but you only need to pay the monthly due to avoid interest.

If you can provide a screen shot of what you see, obscuring any personal data, then maybe someone can clarify what is going on.