Credit card interest is expensive right now. According to the Federal Reserve’s G.19 consumer credit release, commercial banks charged an average of 22.36% on credit card accounts that were assessed interest in August 2026, up from 22.15% in May. Against that backdrop, a card advertising 0% for 15 or 18 months looks like free money.
It can be close to free. It can also cost more than you expected. The difference is almost always in terms that sit below the headline: how long the rate actually lasts, what it applies to, what it costs to move a balance and what happens on the day it ends.
What “0% intro APR” actually covers
An introductory rate can apply to purchases, balance transfers or both, and the two don’t always last the same length of time. A card might offer 0% on transfers for 18 months but on purchases for only 12. Read the rate table in the card agreement (the box disclosures issuers must provide) rather than the marketing page.
Check three lines in that table:
- The intro period length, and whether it’s counted from account opening or from the first transfer.
- The deadline for transfers. Many cards require balance transfers to be completed within 60 or 120 days of opening to get the intro rate.
- The go-to rate, the APR that applies once the promotion ends. It’s often a range set by your credit profile.
The balance transfer fee is the real price
A 0% balance transfer is rarely zero-cost. Most cards charge a transfer fee, commonly 3% to 5% of the amount moved, and it’s added to your balance on day one. Say you transfer a hypothetical $6,000 balance with a 3% fee: you now owe $6,180. That $180 is your cost of borrowing for the promotional period.
That can still be a great deal compared with a card charging around 22%. It just needs to be compared honestly. If you can pay the balance off in a few months anyway, the fee might cost more than the interest you’d save. Our guide to when a balance transfer card makes sense works through those scenarios.
Zero percent versus “no interest if paid in full”
This distinction trips up more people than any other. They sound similar and work very differently.
| Feature | True 0% intro APR | Deferred interest promotion |
|---|---|---|
| Where it’s common | General-purpose credit cards | Store cards and retail financing |
| Interest during the promo | None charged | Accrues in the background |
| If a balance remains at the end | Regular APR applies to the remaining balance from then on | All interest accrued since the purchase can be charged at once |
| Typical marketing phrase | “0% intro APR for 15 months” | “No interest if paid in full in 12 months” |
With deferred interest, leaving even $50 unpaid on the last day can trigger interest on the entire original purchase, backdated to day one. If you see the phrase “if paid in full,” treat the promotion end date as a hard deadline.
Rules the CARD Act guarantees
Federal law gives intro rates some built-in protection. Under the Credit CARD Act, a promotional rate generally has to last at least six months. During that window, the issuer can’t raise your rate on the promotional balance unless you’re more than 60 days late on a payment, which is one of the few ways to lose the deal early.
The law also controls how payments are applied. Anything you pay above the minimum must go to the balance with the highest interest rate first. That helps if you have a 0% transfer balance and a smaller balance of full-rate purchases on the same card: extra payments go to the expensive balance. The minimum payment itself can still be applied to the 0% portion.
The grace period trap on transfer cards
Here’s a subtle one. On many cards, you only get an interest-free grace period on new purchases if you pay the entire statement balance by the due date. If you’re carrying a transferred balance at 0%, you’re not paying the statement balance in full, so new purchases may start accruing interest at the regular rate right away, unless purchases are also at 0%.
The safest approach is to keep a balance transfer card for the transfer only and put everyday spending elsewhere. The credit card grace period guide explains why it disappears and how to get it back.
How to use one well
A 0% offer pays off when there’s a plan attached to it. A simple version:
- Divide by the months, not the minimum. Take the balance, including any transfer fee, and divide it by the number of promotional months minus one. With a hypothetical $6,180 balance and a 15-month promotion, paying it off in 14 months means about $442 a month, which leaves one month of cushion if something goes wrong.
- Automate that amount. Set autopay for your target payment, not the card’s minimum. Minimums on promotional balances are often tiny and designed to leave a balance at the end.
- Put the end date in your calendar twice: one month out and one week out.
- Don’t add new debt to the old cards. Moving a balance only helps if the original card doesn’t fill back up.
- Never pay late. A late payment can bring a fee, a hit to your score and, after 60 days, the loss of the promotional rate.
Frequently asked questions
Does applying for a 0% card hurt my credit score?
A new application usually triggers a hard inquiry, which may lower your score by a few points for a short time. The new limit can also lower your utilization, which often offsets that over a few months.
Can I transfer a balance between two cards from the same bank?
Usually not. Most issuers don’t allow transfers between their own cards, so the debt typically needs to come from a different bank.
What happens to the balance when the intro period ends?
On a true 0% offer, whatever remains starts accruing interest at the card’s regular APR from that point forward. There’s no backdated interest unless the offer was a deferred interest promotion.
Is a personal loan a better option?
It can be if you need longer than the promotional period or want a fixed payoff date. A personal loan usually charges interest from day one, but its fixed term and payment make it harder to drift past the deadline.
