Store-Card Deferred Interest Can Leave a Large Bill at Month Thirteen
The banner says zero interest for twelve months. What the cardholder agreement says is that interest is deferred, not forgiven. If any promotional balance remains on the last day, retroactive interest may be charged based on daily balances since purchase; the amount depends on the payment history and card terms.
A Sofa and the Interest Waiting Behind It
The CFPB describes a $4,500 furniture purchase on a two-year deferred-interest promotion where the customer pays down most of the balance but still owes $180 when the promotion ends. If the promotional balance is not paid in full by the deadline, the issuer can add interest retroactively based on daily balances going back to the purchase date. The actual charge depends on the payment history and card terms; it is not determined by the small balance left at the end alone.
This is not a penalty for late payment. Every payment was on time. It is the designed outcome of a product called deferred interest, and the word doing the damage is deferred, not zero.
The Interest Was Accruing the Whole Time
A true zero-percent promotion and a deferred-interest promotion look identical on the banner. They are different products in the cardholder agreement. Under a true zero-percent offer, no interest accrues during the promotional window; when it ends, the regular rate applies only to whatever balance is left. Under deferred interest, the interest is being calculated from day one and held in abeyance. The account tracks it silently in the background. The zero on the statement is a temporary courtesy, and it is revocable.
The trigger is binary. Pay the entire promotional balance by the end date, to the dollar, and the accrued interest is waived. Leave any amount, even a rounding error, and the full accrued interest posts at once. There is no partial credit. The agreement calls the waived amount "deferred," which is the institution's honest word for "not forgiven yet, and not forgiven if you slip."
Where the Rate Comes From
The CFPB reported that new cards from the top 100 retailers averaged a 32.66 percent APR in December 2024. Its 22.7 percent general-purpose-card comparison was for 2022, so the figures come from different periods. Retail cards can still carry high rates, and deferred interest adds a separate risk: the CFPB found about one in five promotional balances were charged retroactive interest. That is not a rare edge.
The mechanics reward a specific error. The minimum payment the card sets each month is often calibrated so that paying exactly the minimum does not clear the balance by the promotional deadline. A cardholder who pays what the statement asks, every month, on time, can still arrive at the end date with a balance, and therefore with the full interest charge. The statement's suggested payment and the payment required to avoid the trap are two different numbers, and only one of them is printed in bold.
What the Disclosure Actually Says
The promotional terms are required to state, somewhere, that interest will be charged from the purchase date if the balance is not paid in full by the end of the promotional period. That sentence is the entire product. It is typically not on the banner and not at the register. It is in the terms attached to the offer, in the paragraph that begins with "Interest will be charged to your account from the purchase date if."
The figure a cardholder should locate is not the promotional rate, which is zero and therefore uninformative. It is the balance required to be paid, and the exact end date, both of which the issuer will state on request and on the monthly statement. Divide the promotional balance by the number of months and pay that fixed amount, not the minimum. The document does not tell the borrower to do this. It only tells them what happens if they do not.