How deferred interest works (the 0% trap)

A "0% for 12 months" dental card often isn't 0% interest. It's usually a deferred interest promo: you pay no interest only if you pay the whole balance before the promo ends. If even a few dollars are left, the card charges all the interest that built up since the day of your treatment (CFPB).

The CFPB's own example is a $2,400 root canal and crown on a card with a six-month promo. Paying $400 a month clears it with no interest. If you paid $300 a month instead, you'd still owe $600 at the deadline. By this calculator's math, the back interest at a 26.99% APR would be about $223, added all at once.

The CFPB's 2023 report on medical credit cards found:

Deferred-interest promos on these cards usually last 6 to 18 months.
The typical medical credit card APR is 26.99%, compared with about 16% for general-purpose credit cards.
People paid $1 billion in deferred interest on healthcare purchases from 2018 to 2020.
People were charged deferred interest on 20% of healthcare purchases made with these cards or loans (2015 to 2020). For people with credit scores below 619, it was about 34%.

0% intro APR vs. deferred interest

Read the offer's wording. The CFPB says to watch out for the word "if": "no interest if paid in full within 12 months" means deferred interest. A true 0% intro APR charges interest only on whatever is left after the promo ends, starting from then.

In the CFPB's example, $100 is left from a $400 purchase at a 25% APR. With a true 0% offer you owe $100. With deferred interest you owe $165, and the 25% APR then applies to that whole $165.

How to avoid deferred interest

Work out the payment that finishes in time. Divide the amount you financed by the number of promo months, and round up. For $2,400 over 12 months, that's $200 a month.
Pay that amount every month, on time. You can ask the card company to apply anything above the minimum to the promo balance (CFPB).
Know the exact end date, and plan for your last payment to post before it, not on it.
If you can't afford the payment that clears it in time, compare a regular loan or an in-house plan. For people who can't pay in full during the promo, the CFPB found the cost "substantially exceeds" other available credit.

Loan or card with interest: you pay interest every month on the balance. A longer term means a lower monthly payment but more interest overall (CFPB).
0% promo with deferred interest: free only if you clear it in time. If you don't, it can cost more than the loan.
Dentist's in-house payment plan: ask about it. The CFPB notes that doctors' offices historically offered their own no-cost or low-cost payment plans. It also found that loans arranged directly through a provider tend to have zero or low interest.

Before you finance anything, make sure your insurance has been billed. The CFPB warns that some patients who should be covered by insurance or financial assistance are signed up for a medical card instead. The Dental Insurance Calculator estimates what your plan should pay, so you only finance your share.

Questions to ask before you sign

Is this deferred interest or a true 0% APR? What APR applies after the promo?
On what exact date does the promo end?
What's the minimum payment, and will it clear the balance in time?
Are there any fees to sign up, or for late payments?
Does the office offer its own payment plan?
Has my insurance been billed, and is this amount only my share?

How this tool works

Loans and in-house plans. The monthly payment uses the standard loan formula:

payment = amount × r ÷ (1 − (1 + r)^−months), where r = APR ÷ 12

It's rounded to the cent. Each month, interest is the balance × r, rounded to the cent. The rest of the payment lowers the balance. The last payment is whatever clears the balance exactly, so it can differ by a few cents. At 0% APR, the payment is the amount ÷ months.

0% promos with deferred interest. During the promo, the tool works out each month's interest on the balance you owed that month, at the APR you enter. It doesn't charge it yet. If the balance reaches $0 by the end, none of it is charged. If a balance is left, all of that interest is added at once. The rest is then paid at your monthly payment, with the APR charged monthly. "Pay this to owe no interest" is the amount financed ÷ promo months, rounded up to the cent.

Total cost = down payment + every payment + any one-time fee.

Limits. Real cards calculate interest on the average daily balance, so your statements can differ by a little. The tool assumes on-time payments, no new purchases on the card, and no late fees or penalty APR. It's for comparing offers, not a lender's disclosure. Check the actual terms before you sign.

Frequently asked questions

What is deferred interest on a dental credit card?

It's a promo that charges no interest only if you pay the whole balance by the deadline. If any balance is left, you're charged the interest that built up from the day of your treatment (CFPB).

How much do I need to pay each month to avoid deferred interest?

Divide what you financed by the number of promo months and round up to the next cent. For $2,400 over 12 months that's $200 a month. The card's minimum payment is often lower than that (CFPB).

Is a 0% intro APR the same as deferred interest?

No. With a true 0% intro APR, interest only starts on whatever balance is left after the promo ends. With deferred interest, back interest from the purchase date is added too. In the CFPB's example, $100 left on a $400 purchase becomes $165 with deferred interest.

What interest rate do dental credit cards charge after the promo?

The CFPB found that the typical medical credit card APR is 26.99%, compared with about 16% for general-purpose credit cards. Check the rate on your own offer.

Can I ask my dentist for a payment plan instead?

Yes, it's worth asking. The CFPB notes that providers have historically offered their own no-cost or low-cost payment plans, and that loans arranged directly by a provider tend to have zero or low interest.

Sources

Consumer Financial Protection Bureau. Medical Credit Cards and Financing Plans. May 2023. Accessed October 26, 2026.
Consumer Financial Protection Bureau. CFPB Report Highlights Costly Credit Cards and Loans Pushed on Patients. May 4, 2023. Accessed October 26, 2026.
Consumer Financial Protection Bureau. I got a credit card promising no interest for a purchase if I pay in full within 12 months. How does this work?. reviewed January 22, 2024. Accessed October 26, 2026.
Consumer Financial Protection Bureau. How to understand special promotional financing offers on credit cards. 2017. Archived page. Accessed October 26, 2026.
Consumer Financial Protection Bureau. What is amortization and how could it affect my auto loan?. reviewed September 24, 2024. Accessed October 26, 2026.

Last reviewed October 26, 2026 by the Dental Health Time editorial team, against the sources above. How we review.