What happens to my old credit card after a balance transfer?

The original card stays open with a zero balance — the transfer pays off the original account. Keeping it open (but not using it) usually helps your credit score by preserving your credit limit and account age. Closing it can drop your credit utilization ratio and shorten your credit history, both of which can ding your score. Cut up the card if you don't trust yourself, but leave the account open.

Last updated April 24, 2026

Promo APR Math

Balance Transfer Calculator

Q: Are balance transfers actually worth it?

Only if two things are true. First, the interest you save on the promo APR is larger than the transfer fee (usually 3–5% of the balance). Second, you can realistically pay off most or all of the balance before the promo period ends — otherwise the remaining balance starts accruing at the post-promo rate (often 20%+) and the math can flip against you. This calculator models both.

Q: What is a typical transfer fee?

Most balance transfer offers charge 3% of the transferred balance, with some charging 5% and a rare few charging 0% as a promotional sweetener. On a $5,000 balance, a 3% fee adds $150 up front. That fee is added to the new card's balance immediately, so you're already behind — the promo APR has to save you more than $150 in interest for the transfer to be worth it.

Q: What's the post-promo APR and why does it matter?

Once the promo period (typically 12–21 months) ends, whatever balance is left jumps to the card's standard APR — often 20–29%, sometimes higher than what you started with. If you still have $3,000 left when the promo ends, that remaining balance can rapidly eat the savings you earned during the promo. The calculator shows you exactly how much balance remains when the promo ends.

A 0% balance transfer isn't free — there's a transfer fee and a post-promo APR waiting at the end. See whether the math actually works out before you move your balance.

Currency region: Amounts in CAD

Your Current Card

Current Balance ($)

Current APR (%)

Monthly Payment ($)

Transfer Offer

Promo APR (%)

Usually 0%

Promo Length (months)

Transfer Fee (%)

Typically 3–5%

Post-Promo APR (%)

Transfer saves

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Stay payoff

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Transfer payoff

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Transfer fee

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Net savings

—

Total cost (interest + fee)

Stay

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Transfer

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What the math is really doing

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The catch: balance transfers only work if you actually pay down the balance during the promo. If you keep charging the new card or treat it as "free money," you'll end the promo with a big balance at 20%+ APR — often worse than where you started.

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How balance transfers actually work

A balance transfer moves debt from a high-rate credit card to a new card offering a promotional 0% or low-APR period. The new issuer pays off the old balance in exchange for a fee, typically 3 to 5% of the amount moved, and gives you six to twenty-one months of interest-free runway to pay it down. On paper, the math is obvious: every month at 0% is a month you keep the roughly $150 to $200 you would have paid in interest on a $10,000 balance at 22%.

The real math is less obvious, because the fee and the time limit interact. A 3% fee on $10,000 is $300 added to your balance on day one. You need to save at least that much in interest during the promo period for the transfer to come out ahead. At a 22% APR, you would have paid about $183 in interest in the first month alone, so the fee pays itself back in under two months. But if you only carry the balance for four months before selling a paid-down balance to paying it off, the saved interest is $732 and the fee is still $300, which leaves $432 ahead. If you cannot finish the payoff before the promo ends and the rate resets to 23% on whatever remains, most of the savings evaporate.

The transfer-fee arithmetic

The breakeven rule is simple. Divide the transfer fee by your current monthly interest cost. The result is the number of months of promo period you need to break even. On a $6,000 balance at 24% APR with a 3% transfer fee, the fee is $180 and the current monthly interest is $120. The transfer breaks even in 1.5 months. Any promo period longer than that is saved money, provided the balance is actually being paid down during it.

The arithmetic that catches people is the post-promo rate. When the 0% window expires, the remaining balance starts accruing at the card's regular purchase APR, which is often the same or worse than the card you transferred from. The savings only exist for the portion of the balance cleared during the promo. Anything left becomes regular debt at regular rates, and the transfer fee is sunk.

What breaks the math

Three patterns turn a balance transfer into a loss. The first is continuing to use the old card. If you transfer $8,000 off a card and then run the balance back up to $3,000, you now have two cards accruing interest instead of one, and you paid a fee for the privilege. The cleanest play after a transfer is to freeze the old card physically, not just mentally.

The second is minimum-payment drift. If you treat the 0% window as a reason to relax and pay only the new card's minimum, the balance barely moves. Promotional periods tend to end when most of the debt is still there, which is exactly when the post-promo rate hits. The payoff target should be to clear the entire balance inside the promo window, which usually means a fixed monthly payment that stays level.

The third is triggering the fine print. Many 0% offers end the promo retroactively if you miss a single payment by more than 60 days, which means the entire balance becomes subject to the regular rate back-dated to the transfer date. One late payment can cost you the full interest you thought you avoided.

When a transfer is the wrong move

If your balance is small enough that you can pay it off in three to six months by staying put, the transfer fee probably costs more than the interest you avoid. The threshold is roughly whether the fee exceeds the interest you would pay by staying. For smaller balances under $2,000, consolidation via a personal loan or just paying aggressively often beats the transfer.

If your credit score is below roughly 670, most 0% offers will not approve, and the ones that do may come with shorter promo periods or higher fees. Applying and being denied creates a hard inquiry that drops your score further, so it is worth checking pre-qualification offers that use a soft pull first.

If you expect income instability inside the promo window, a transfer is a bet you might not be able to honour. The worst version of a balance transfer is one where you pay the fee, then lose your job three months in, then carry the balance past the promo at the reset rate.

The one-page decision

Three questions decide it. Can you pay more than the fee's worth of interest during the promo? Will you finish the payoff before the window closes, not just the promo period? Will you stop using the old card? If all three are yes, the transfer is money. If any one is no, you probably belong in an avalanche or snowball payoff on your existing cards instead.

Common Questions

Are balance transfers actually worth it?

Only if two things are true: the interest you save on the promo APR is larger than the transfer fee (usually 3–5% of the balance), AND you can realistically pay off most of the balance before the promo period ends. Otherwise the leftover balance starts accruing at the post-promo rate (often 20%+) and the math can flip against you.

What is a typical transfer fee?

Most offers charge 3% of the transferred balance, with some charging 5% and a rare few charging 0% as a promotional sweetener. On a $5,000 balance, a 3% fee adds $150 up front. That fee is added to the new card's balance immediately — so the promo APR has to save you more than $150 in interest for the transfer to be worth it.

What happens to my old credit card after a transfer?

The original card stays open with a zero balance. Keeping it open (but not using it) usually helps your credit score by preserving your total credit limit and account age — closing it can drop your credit utilization ratio and shorten your credit history. Cut up the card if you don't trust yourself, but leave the account open.

What's the post-promo APR and why does it matter?

Once the promo period ends (typically 12–21 months), any remaining balance jumps to the card's standard APR — often 20–29%, sometimes higher than what you started with. If $3,000 is left when the promo ends, that balance will rapidly eat the savings you earned during the promo. This calculator shows you exactly how much balance remains when the promo expires.

Can I transfer more than one balance?

Yes, most cards let you transfer multiple balances up to the new card's credit limit. The transfer fee usually applies to each transfer separately. Add your balances together and use this calculator on the combined total, treating the weighted-average APR of your old cards as the "current APR."

Will a balance transfer hurt my credit score?

Short-term, yes — applying for the new card triggers a hard inquiry (typically 5–10 points for a few months) and a brand-new account shortens your average account age. But if you actually pay down the balance, your credit utilization drops significantly, which usually outweighs both negatives within 3–6 months and often leaves your score higher than before.