When the 0% APR promotion ends on a credit card, whatever balance you haven’t paid off starts accruing interest at the card’s regular variable rate, which averages around 22% for bank-issued cards as of early 2026. That rate was disclosed in your card agreement before you accepted the offer, and it applies to the leftover balance and to every new purchase going forward. The bigger question is whether your promotion was a true 0% APR or a deferred interest arrangement, because those two look identical on your statement and behave very differently the moment the deadline passes.
True 0% APR Is Not the Same as Deferred Interest
A true 0% introductory APR means no interest accrues during the promotional window. When it ends, the remaining balance simply starts generating interest from that day forward at the regular rate. Nothing is charged retroactively.
Deferred interest works the opposite way. Interest is calculated from the date of each purchase the entire time, but it’s held back from your statement. Pay the balance to zero before the deadline and those charges disappear. Carry even a small balance past the deadline, and all of the accumulated interest gets added to your account in a single hit.
The wording on your agreement tells you which you have. A true 0% offer reads like “0% intro APR on purchases for 15 months.” A deferred interest offer uses conditional language: “no interest if paid in full within 12 months.” That “if” is the tell.1Consumer Financial Protection Bureau. How to Understand Special Promotional Financing Offers on Credit Cards Deferred interest deals are especially common on retail store cards for furniture, electronics, and appliances.
The Rate That Kicks In
The post-promotional rate is disclosed in the summary table that came with your card application, alongside the length of the promotional period. Most introductory windows run between six and 21 months.
That ongoing rate is almost always variable. Your agreement defines it as the U.S. Prime Rate plus a fixed margin. As of late 2025, the Prime Rate sits at 6.75%.2Federal Reserve Bank of St. Louis. Bank Prime Loan Rate Changes: Historical Dates If your card’s margin is 15 percentage points, the purchase APR works out to 21.75%. When Prime moves, your rate moves with it.
Under federal law, an issuer can raise your rate after a promotion only if the promotion lasted at least six months and the post-promotional rate was disclosed in writing before it began.3eCFR. 12 CFR 1026.55 – Limitations on Increasing Annual Percentage Rates, Fees, and Charges One additional protection: the regular rate can only apply to transactions made during or after the promotional period, not to balances that existed before it started.4Office of the Law Revision Counsel. 15 USC 1666i-1 – Limits on Interest Rate, Fee, and Finance Charge Increases Applicable to Outstanding Balances
How the Deferred Interest Trap Plays Out
This is where people get hurt. During the promotion, your statement may show $0 in interest charges, which feels identical to a true 0% offer. The lender is calculating interest daily the whole time, though, and the full amount posts to your account if the balance isn’t zero by the deadline.
Consider a $3,000 television financed on a 12-month deferred interest plan at a 29.99% APR. Even if you’ve paid the balance down to $200 by month 11, the accumulated interest from the entire year gets assessed because you didn’t reach zero. On a 12-month period near a 30% APR, that retroactive charge can easily exceed $400.
These arrangements are all-or-nothing. Paying 95% of the balance does nothing to reduce the retroactive charge. Only bringing the balance to exactly zero before the deadline avoids it. Retail card APRs regularly reach the mid-30% range, which makes the penalty steeper still.
How Monthly Interest Is Calculated Once It Starts
Once interest is accruing, most issuers use the average daily balance method.5Consumer Financial Protection Bureau. How Does My Credit Card Company Calculate the Amount of Interest I Owe? The APR is divided by 365 to produce a daily periodic rate. Each day’s balance is multiplied by that rate, and the daily amounts are totaled at the end of the cycle.
A $2,000 balance at 22% APR produces a daily rate of roughly 0.0603%. Over a 30-day cycle with no payments, that comes to about $36 in interest. That interest gets added to the balance, so the next month’s calculation runs on $2,036. This is why balances grow faster than expected when only minimums are paid.
Where Your Payments Go When Rates Differ
After a promotion ends, a single card can carry balances at different rates: leftover promotional purchases at the regular APR alongside new purchases at that same rate, or a mix that includes a deferred balance still counting down. Federal rules control the allocation. Anything you pay above the required minimum must be applied first to the balance with the highest interest rate, then the next highest.6eCFR. 12 CFR 1026.53 – Allocation of Payments
For deferred interest balances, the rule flips in your favor near the end. During the last two billing cycles before the deferred interest deadline, any payment above the minimum must go to the deferred balance first.6eCFR. 12 CFR 1026.53 – Allocation of Payments The minimum itself is allocated at the issuer’s discretion, so paying only the minimum in those final months rarely puts enough toward the deferred balance to help.
How You Can Lose the 0% Rate Early
The promotional rate isn’t guaranteed to last the full window. If you miss a minimum payment by more than 60 days, the issuer can revoke the promotion and impose a penalty APR, which typically runs close to 30%. That penalty rate can apply to your existing balance, not only future purchases.3eCFR. 12 CFR 1026.55 – Limitations on Increasing Annual Percentage Rates, Fees, and Charges
There is a way back. Six consecutive on-time minimum payments after the penalty rate takes effect requires the issuer to drop the rate back to what it was before.4Office of the Law Revision Counsel. 15 USC 1666i-1 – Limits on Interest Rate, Fee, and Finance Charge Increases Applicable to Outstanding Balances Issuers are also required to review the penalty rate at least every six months and reduce it if conditions warrant.7eCFR. 12 CFR 1026.59 – Reevaluation of Rate Increases Six months of penalty interest on a large balance still adds up, so automating the minimum payment is worth doing.
What Changes on Your Statement
Minimum payments rise. Most issuers set the minimum at roughly 1% to 3% of the balance plus any interest and fees. During the promotion, the interest component was zero. Once the regular APR kicks in, that charge layers on top. A minimum of $40 during the promo might climb to $65 or $75.
You also lose the grace period on new purchases. Carrying a balance into a billing cycle means interest starts accruing on new charges from the transaction date rather than from the statement closing date.8Consumer Financial Protection Bureau. What Is a Grace Period for a Credit Card You don’t get the grace period back until you pay the full statement balance for a complete cycle. During the 0% window this didn’t matter; after it, every swipe starts costing you.
Your credit score can slip as well. When interest inflates your reported balance, credit utilization rises with it, and utilization drives roughly 30% of a FICO score. A card at 40% utilization before the promotion ended might drift to 45% or 50% after a few months of interest compounding onto the principal.
What to Do Before the Deadline Hits
Paying the balance to zero before the promotion expires is the cleanest outcome. If that isn’t realistic, a few options limit the damage.
- Balance transfer to a new 0% card. Moving the remaining balance to another card with its own introductory 0% APR restarts the interest-free clock. Transfer fees usually run 3% to 5% of the amount moved, so a $5,000 balance costs $150 to $250 upfront. That’s still far cheaper than months of 22%+ interest.
- Accelerated payments. If a new card isn’t available or appealing, redirecting discretionary spending toward extra payments in the final months of the promotion shrinks the balance that will be exposed to interest. An extra $100 to $200 a month makes a real difference.
- Personal loan consolidation. A fixed-rate personal loan with a lower APR than your card can work for larger balances. The rate won’t be zero, but personal loan rates for borrowers with decent credit often sit well below credit card rates, and the fixed schedule forces the balance down.
- Nonprofit credit counseling. If the balance feels unmanageable, a nonprofit credit counseling agency can negotiate a debt management plan with your issuer. Setup fees typically run $75 or less, and these plans often secure a reduced rate.
The date to work backward from is the one printed on your original card agreement or financing contract. Put it on the calendar with enough lead time to act. Most people caught by the rate transition knew the promotion was ending and assumed they’d deal with it later, and later arrived faster than the balance went down.