Will you pay off your 0% promo balance in time — or get hit with the backdated interest bomb?
| Mo. | Payment | Balance | Interest Hiding | Penalty If You Stop Now |
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Promotional financing offers from retailers — CareCredit, Synchrony Bank (Amazon, Walmart, Ashley Furniture, Rooms To Go, Jared), and GreenSky — advertise "0% interest for 12/18/24 months." The catch buried in the fine print: interest is quietly accruing the whole time. If you pay off the full balance before the deadline, those charges are waived. If even $1 remains, every dollar of accumulated interest from the entire promotional period gets added to your balance at once. It's retroactive.
No — and this distinction is worth hundreds or thousands of dollars. A true 0% APR (common on bank credit cards like Chase Freedom and Citi) means interest genuinely does not accrue. If you have $50 left on day 365, you owe $50. With deferred interest, that same $50 balance triggers 12+ months of backdated interest charges. Look for the phrase "No Interest if Paid in Full" in the promotional terms — that's the red flag that means deferred interest, not true 0%.
Each month, this calculator applies your deferred APR to your remaining balance and tracks the hidden interest as it builds. Your payments reduce the principal only — no interest is added to your running balance during the promo. At the end of the promotional period, if any balance remains, every month's worth of hidden interest is totaled and added at once. The "Penalty If You Stop Now" column in the table shows you what that number would be at any given month — so you can see the clock ticking.
Minimum payments on deferred interest accounts are typically 1–3% of the balance — designed to keep you in the promotional period without paying it off. At a $2,500 balance, that's $25–$75/month, far short of what's needed to clear the debt before the deadline. This calculator shows you the actual required monthly payment to reach $0 in time.
CareCredit (medical, dental, vision, veterinary), Synchrony Bank (powers many store cards including Amazon Store Card, Sam's Club, Lowe's, Ashley Furniture, Rooms To Go, Jared, Mattress Firm), GreenSky (home improvement), and many in-store financing offers from furniture, electronics, and jewelry retailers. If a retailer says "12 months same as cash" or "no interest if paid in full," that is almost always deferred interest.
You have a few options: (1) Call your lender and ask to convert to a standard installment loan — some will do this. (2) Transfer the balance to a true 0% APR credit card before the deadline (balance transfer fees are usually 3–5%, much less than the backdated interest). (3) Pay as much as you can before the deadline to reduce the penalty, then deal with the remaining interest. Any of these is better than missing the deadline entirely.