Promotional financing offering no interest for a period comes in two forms that look identical at the point of sale. One waives interest during the term; the other only defers it.
Waived and deferred are different products
An offer that waives interest charges nothing on the balance during the promotional period. Any amount left at the end simply starts accruing from that point forward.
An offer that defers interest calculates it throughout the period and holds it in the background. It is charged only if a condition is not met, and it is charged in full.
Both are advertised as no interest. The distinction sits in the agreement rather than in the headline.
The condition is usually clearing the whole balance
Deferred interest is typically written off only if the entire promotional balance is repaid by the end date. Paying most of it does not qualify for partial relief.
A small remaining amount therefore triggers the full accumulated interest calculated on the original balance across the whole period, not on the residual.
The charge can be large relative to what was outstanding, which is why the outcome surprises people who believed they were nearly finished.
Minimum payments do not clear the balance
The minimum payment on these arrangements is generally set to a level that will not retire the balance within the promotional term. Meeting it every month is not sufficient.
Because the account appears in good standing throughout, nothing signals that the trajectory misses the deadline. The statement shows compliance, not adequacy.
Clearing the balance in time requires dividing it by the number of months and paying that amount, which is usually well above the stated minimum.
Payment allocation can work against the plan
Where a card carries both a promotional balance and ordinary purchases, how payments are allocated between them determines what is actually being reduced.
Rules on allocation vary by product and by jurisdiction, and some arrangements direct payments to the balance the issuer prefers rather than the one the customer intends.
Keeping promotional purchases on a dedicated account avoids the ambiguity, since every payment then reduces the balance with the deadline attached.
Why the structure exists at all
Deferred interest lets a retailer offer a genuinely attractive headline while the lender retains the possibility of full interest income. It is priced on the expectation that a share of borrowers will miss.
Used deliberately, with the balance divided across the term and cleared before the date, the offer costs nothing and works exactly as presented.
The risk is entirely in the ending, which is the part that receives the least attention when the agreement is signed.