Deferred Interest Calculator
For "no interest if paid in full" store card and retail financing offers: see the interest building up in the background, the payment that avoids it, and what you owe if you miss the deadline.
Updated · Published · Built by Ali Ahmad, Founder
Calculation method: This calculator uses a simplified monthly-interest model (APR ÷ 12). Credit-card issuers may calculate interest using daily periodic rates and average daily balances, so your actual statement may differ. See our methodology.
Deferred Interest Calculator
On a deferred-interest offer ("no interest if paid in full within 12 months"), interest builds up at the card's APR from the purchase date. Pay the whole promo balance by the deadline and it is never charged; leave even $1 and all of it is added at once. To be safe, pay at least the purchase amount ÷ the promo months, and finish a month early.
Deferred interest is common on store credit cards and retail financing for furniture, electronics, appliances and medical bills. It looks like a 0% offer, but it isn't one: a true 0% intro APR charges interest only on what's left after the promo, while a deferred-interest plan charges back interest on the full purchase, from day one. This calculator shows how much interest is building up behind the "no interest" label and what you'd pay if you miss the deadline.
How the Calculator Works
Enter the purchase amount, the length of the promotion, the card's APR and your monthly payment. The calculator:
- Divides the purchase by the promo months to find the payment that clears it in time, rounded up to the cent.
- Runs the promotion month by month: interest builds at APR ÷ 12 on the promo balance, then your payment reduces the balance. The interest is tracked separately, not added to the balance.
- If the balance reaches $0 within the promotion, the built-up interest is waived. If not, all of it is added to what you still owe.
- Runs that new balance through the monthly model at the card's APR, at the same payment, to show the total interest.
Formula
Deferred Interest = sum over each promo month of (Promo Balance × APR ÷ 12)
If any balance is left at the deadline: New Balance = Balance Left + Deferred Interest
This is a simplified monthly estimate. Issuers usually accrue deferred interest daily on the average daily balance, so your statement figure may differ by a few dollars.
Example: $2,000 on a 12-month "no interest if paid in full" offer at 29.99%
| Monthly payment | Left at the deadline | Deferred interest charged | Total interest |
|---|---|---|---|
| $166.67 ($2,000 ÷ 12) | $0.00 | $0.00 ($324.89 waived) | $0.00 |
| $150 | $200.00 | $352.38 | $386.84 |
| $100 | $800.00 | $434.86 | $695.14 |
| $60 | $1,280.00 | $500.83 | $2,010.97 |
Paying $150 instead of $166.67 leaves only $200 unpaid, but it costs $352.38 in deferred interest the day the promotion ends, for a new balance of $552.38 that takes 4 more months to clear. On a true 0% intro APR offer, the same $200 shortfall would cost about $6.37 in interest at the same rate (see the 0% Intro APR Calculator). That gap is the whole difference between the two kinds of offer.
Deferred Interest vs. 0% Intro APR
| Deferred interest | 0% intro APR | |
|---|---|---|
| Usual wording | "No interest if paid in full within 12 months" | "0% intro APR for 12 months" |
| Interest during the promo | Builds up in the background at the full APR | None |
| Balance left at the end | All built-up interest is charged back to the purchase date | Interest starts on the leftover balance only |
| Where it's common | Store cards, retail and medical financing | Bank cards, balance transfers |
How to Avoid Paying Deferred Interest
- Pay more than the minimum. The required minimum on a deferred-interest plan is often too small to clear the balance in time. The CFPB warns that paying only the minimum can leave you owing the deferred interest.
- Finish a month early. The promotion's end date is printed on your statement and may not match your payment due date. Aiming one month ahead leaves room for a payment that posts late.
- Don't be more than 60 days late. The CFPB notes that a payment more than 60 days late can end the promotion early and trigger the deferred interest.
- Watch other balances on the same card. Payments above the minimum normally go to the highest-APR balance first, but under Regulation Z § 1026.53, in the last two billing cycles before a deferred-interest promotion ends, the issuer must put the excess toward the deferred-interest balance first. Before that, new purchases can soak up payments you meant for the promo.
- Consider moving it. If you can't clear it in time, a 0% balance transfer before the deadline may cost less; compare with the Balance Transfer Calculator.
When the Result May Differ
Treat the results as a planning estimate. Your real numbers can differ because of:
- Daily accrual: issuers usually calculate deferred interest daily on the average daily balance, and the timing of your payments within each cycle changes the total.
- Several promotions on one card: store cards often carry more than one promotional purchase, each with its own deadline, plus regular purchases at the standard APR.
- Fees: late fees and other charges aren't included. See Credit Card Late Fees Explained.
- New purchases: the estimate assumes the promo purchase is the only balance.
Your statement and cardholder agreement are the final word. See our methodology for how every calculator on this site works.
Frequently Asked Questions
What is deferred interest?
Deferred interest is a promotion, usually worded "no interest if paid in full within" a set number of months, where interest builds up at the card's regular APR from the purchase date. If you pay the whole promotional balance by the deadline, that interest is waived. If any of it is left, the issuer charges all of the built-up interest at once.
Is deferred interest the same as 0% APR?
No. With a true 0% intro APR, no interest builds during the promotion, and only the balance left at the end starts accruing interest. With deferred interest, interest on the full purchase is charged back to day one if you miss the deadline. On a $2,000 purchase at 29.99%, a $200 shortfall costs about $352 under deferred interest, but only about $6 under a 0% intro APR.
Is the deferred interest charged only on the amount I still owe?
No. It is the interest that built up on the whole promotional balance, month by month, from the purchase date, even on the part you already paid off. That is why a small leftover balance can bring a large interest charge.
Will the minimum payment pay off a deferred-interest purchase in time?
Often not. The CFPB warns that paying only the minimum may leave a balance at the end of the promotion, which triggers the deferred interest. Divide the purchase by the promo months and pay at least that much.
Can a late payment trigger deferred interest early?
The CFPB notes that being more than 60 days late on a payment can end the promotion and trigger the deferred interest. A shorter late payment can still bring a late fee, so check your card's terms.
How are payments applied if my store card has other balances?
Amounts above the minimum generally go to the highest-APR balance first. Under Regulation Z § 1026.53, during the last two billing cycles before a deferred-interest promotion ends, the issuer must apply the excess to the deferred-interest balance first. Earlier in the promotion, new purchases on the card can slow payoff of the promotional balance.
This calculator provides estimates for educational purposes only and is not financial, tax, or legal advice. Most results use a simplified monthly-interest model (APR ÷ 12); your card issuer may use a daily periodic rate and average daily balance, plus its own fees and grace period rules, so your actual figures may differ — always confirm against your official statement.
Sources
- I got a credit card promising no interest for a purchase if I pay in full within 12 months. How does this work? — Consumer Financial Protection Bureau. Checked September 25, 2026.
- Regulation Z § 1026.53 – payments above the minimum go to the highest-APR balance first — Consumer Financial Protection Bureau. Checked September 25, 2026.
- Regulation Z § 1026.55 – limits on raising APRs, including the 60-days-late rule — Consumer Financial Protection Bureau. Checked September 25, 2026.