What happens after 0% APR ends on a balance transfer

When a 0% balance transfer promotion ends, whatever is still owed starts accruing interest at the card’s go-to APR from the next billing cycle. Nothing is charged for the months that already passed. The cost is entirely a function of how much is left and what the go-to rate is, and both of those are known in advance. The calculator above prints the remaining balance at promo end and the interest it will generate.

The cliff, stated plainly

The CFPB’s 2025 market report puts it in one sentence: “If the consumer has not paid off that balance or completed another balance transfer by the end of the promotional period, any remaining balance becomes subject to the higher non-promotional interest rate.”

Two numbers decide what that costs. The first is the leftover. Citi’s CFO told an earnings call that about half of promotional balances are not paid in full by the time the 0% intro APR ends, and a LendingTree consumer report found two in five balance-transfer cardholders did not clear the transferred balance before expiry. So the leftover is the normal case, not the failure case.

The second is the go-to APR. Post-intro variable rates quoted today generally run from about 17% to 30%, with a midpoint near 22% to 23%. The Federal Reserve’s G.19 series for accounts assessed interest was 22.15% in Q2 2026. Federal Reserve research on promotional cards found rates jumped by roughly 16 percentage points on average when promotions ended.

No retroactive interest, and why the distinction matters

On a genuine 0% APR card, the promotional months were genuinely interest-free. The go-to rate applies from expiry forward and only to the principal still outstanding. There is no back-billing.

Deferred interest works differently, and the two get confused constantly. A deferred interest promotion, typically on a retail store card, accrues interest at the retail APR from the purchase date the whole time. If any balance remains when the promotion ends, the entire accrued amount is added to the account at once. The National Consumer Law Center’s worked example: a $2,500 purchase at 24% with $100 left at month 12 produces nearly $400 in retroactive interest. Note the shape of that: $100 of leftover triggers $400 of charges.

Because the phrasing on the offer decides which product you have, it is worth reading the exact words. Deferred interest is disclosed as “no interest if paid in full within X months”, never as 0% APR. Deferred interest vs 0% APR sets the two side by side with its own calculator.

You will not get 45 days’ notice

Credit card issuers normally have to give 45 days’ written notice before a significant change in account terms, under 12 CFR 1026.9(c)(2)(i). The end of a disclosed promotional period is carved out of that requirement by 1026.9(c)(2)(v)(B): no advance notice is required for the rate increase at the expiry of a previously disclosed promotional period, provided the length of the period and the post-expiration rate were disclosed in writing and prominently near the intro rate, and the new rate does not exceed what was disclosed.

The practical reading is that the warning already happened, in the paperwork at account opening. The date is not a surprise the issuer is obliged to repeat. Two related protections do still apply: 12 CFR 1026.55(b)(1) requires a promotional rate to run at least six months, and 1026.55(b)(4) means the promotion can only be revoked early if a minimum payment is more than 60 days late. A single late payment under 60 days does not end a US promotional rate on the existing balance, whatever the folklore says.

Worked example: $2,450 left at 24%

Someone finishes an 18-month promotion with $2,450 still on the card and keeps paying $150 a month. The go-to APR is 24%, which is 2% a month.

Month one: interest of $2,450 x 0.02 = $49.00. The $150 payment clears that plus $101 of principal, leaving $2,349.

That pattern repeats on a shrinking balance. Running it to zero, the balance takes about 21 more months to clear and generates roughly $546 in interest. Total paid on that $2,450 leftover: about $2,996.

Two things stand out. First, the $49 first month is the interest cost of one month of delay, so bringing the balance down before the expiry date is worth about $49 per $2,450 per month. Second, if the same person had raised the payment to $250 a month during the promotion and arrived at expiry owing nothing, the entire $546 disappears. The leverage is almost all before the date, not after.

Many calculators quietly omit this post-promotional interest and report the savings as if the balance vanished at expiry. On the numbers above that overstates the saving by roughly 21%.

Options at the expiry date

Pay it down before the date. This is the only option with no new cost attached. Divide the current balance by the months remaining and compare that against the current payment. The minimum payment page explains why paying the minimum will not get there: a typical formula of 1% of the statement balance plus interest and fees, with a floor around $40, is designed to keep the account current, not to clear it.

A second transfer to a new card. This works while the new fee is smaller than the interest avoided. On $2,450, a 3% fee is $73.50 against $546 of interest, so the arithmetic is comfortable. On a $600 leftover with three months of payments left, it is not. Bear in mind that a second card means a new application, a new hard inquiry, a new account, and a promotional clock that starts at account opening rather than when the transfer posts. Multiple cards covers the mechanics of chaining transfers.

A personal loan. A fixed rate and a fixed end date suit people who want the debt to have a deadline. NerdWallet’s pre-qualification data by tier gives average APRs of 14.87% for excellent credit, 19.59% for good, 23.84% for fair and 27.28% for bad. At the fair tier, 23.84% is barely below a 24% card rate, so the loan wins on structure rather than on price. Origination fees of 1% to 10% are common and either come out of the proceeds or get added to the principal. Balance transfer vs personal loan runs both side by side.

Doing nothing. Worth naming as a real option, because for a small leftover repaid quickly the interest may be a few tens of dollars and not worth a new application.

The January and February pattern

Balance transfer sign-ups spike in January and February, driven by holiday debt and a seasonal surge in issuer direct mail. Card balances hit records above $1.2 trillion in late 2025, and Google Trends shows searches for balance transfer terms peaking in the first quarter of 2026.

Promotional periods on those cards run 12 to 21 months, with LendingTree finding 82% of 0% balance transfer cards offering either 12 or 15 months. So a card opened in January 2026 expires somewhere between January 2027 and October 2027, and the whole cohort arrives at its cliff in a predictable wave.

If a card was opened in a January or February, the useful thing to do is look up the exact expiry month in the original offer documents now, work out the balance that will be left on the current payment, and decide which of the options above applies while there is still time for the cheapest one to work.