If you're carrying a balance on a credit card and paying interest on it, a 0% balance transfer card allows you to move that debt to a new card where no interest is charged for a set promotional period. This means repayments go toward reducing the balance rather than servicing interest, for as long as the 0% period lasts.

It's worth knowing that 0% periods can vary massively between providers on these cards. However, don't assume that the longer the interest-free period, the better. Opting for a card with a shorter 0% period might be a cheaper option. Here's why.

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How do balance transfer credit cards cards work?

Balance transfer cards are specialist credit cards designed to move debt from an existing card onto a new one. When you apply for a balance transfer card, you'll be given the option of transferring debt over from your old card. The amount you can transfer depends on the credit limit you're offered.

Once you've shifted debt, you'll owe your new card instead. The market's longer balance transfer offers come with correspondingly longer 0% periods, meaning no interest is charged on the transferred amount for the full duration of the period.

Interest-free periods vary between cards, with the longest deals offering more than two years at 0%. While it might seem best to go for the longest 0% period possible, this isn't always the case — more on that below.

How do 0% lengths on 0% balance transfer credit cards work?

Once accepted for a 0% balance transfer credit card, you can move debt from other credit cards onto it. Anything transferred across benefits from a fresh interest-free period, meaning no interest is charged for its duration, provided the main balance transfer rules are followed (explained below).

Based on a review of major credit card comparison sites and provider pages as of September 2026, the longest 0% balance transfer period available reaches up to 38 months, though the actual length offered to an individual applicant may be shorter depending on their credit profile — for example, some applicants accepted for the longest cards receive 32 or 35 months rather than the full 38. Other providers offer periods of up to around 36 months. This reflects the sources checked and may not capture every card on the market; the specific providers offering the longest deals change regularly.

Transfer fees on the longest deals typically run between 3.45% and 3.49% of the balance moved. Some cards advertise a guaranteed 0% period, meaning all accepted applicants receive the full advertised length; others advertise an "up to" figure, with a shorter fallback period for some applicants.

Always make sure you can afford repayments.

What are the main rules to follow with balance transfer credit cards?

If you're planning to get a balance transfer credit card, there are some important rules to understand. Falling foul of any of these could mean losing a 0% deal, or facing higher interest than expected.

1. Avoid spending or withdrawing cash on these cards

Unless otherwise stated, the 0% rate on balance transfer credit cards typically only applies to transferred debt. Using a balance transfer card for purchases or cash withdrawals will usually mean paying interest on those transactions at the card's standard rate. Generally, these cards work best when used only to shift existing debt to 0%.

If you are looking for a credit card to finance a new purchase, take a look at our best 0% purchase credit cards guide.

2. Make at least the minimum monthly payment

Balance transfer credit cards with a 0% period still require at least the minimum monthly payment to keep the interest-free period active — "0%" doesn't mean nothing is owed each month. Setting up an automatic direct debit for the minimum payment, as soon as the card is accepted, helps avoid missing this.

3. Plan to clear your balance within the 0% period

If you're accepted for a balance transfer card pay close attention to the length of the 0% period. Always plan to clear your debts before the interest-free period ends. If you don't, you'll have to start paying interest.

Making more than the minimum monthly payment is generally needed to clear the balance within the 0% period, rather than just keeping the deal alive.

If the balance isn't cleared before the 0% period ends, applying for a new 0% balance transfer card is an option — though acceptance for a new card is never guaranteed, and 0% balance transfer terms can change over time, potentially becoming less generous than they are today.

4. The balance usually needs transferring within a set period to get the headline 0%

Most balance transfer credit cards will stipulate that in order to grab the headline 0% rate, you must transfer your balance within a set period. Commonly around 30 - 60 days or so, though it varies between providers. Checking the specific terms of an offer before applying avoids missing the 0% rate as a result of this window closing.

5. Balances usually can't be transferred within the same banking group

Balance transfer providers usually don't allow transferring debt from a card within the same banking group — for example, a balance can't typically be moved from a Halifax card to a Lloyds card, since they're part of the same group. Checking the terms of a balance transfer offer at the time of application will usually specify which providers are treated as part of the same group.

What about a shorter 0% balance transfer card?

The longest balance transfer cards can seem like the obvious choice, and this can make sense for those who genuinely need a long time to clear existing debt.

However, the longest cards typically charge a one-off transfer fee, usually a percentage of the debt being moved — and the highest fees are generally attached to the longest 0% periods.

For those who can clear their balance within a shorter timeframe, fee-free balance transfer cards are worth considering. These typically offer shorter 0% periods than the longest deals on the market, but no transfer fee applies.

Based on the same review referenced above, as of September 2026, the longest 0% balance transfer period reaches up to 38 months, with the leading cards at this length charging a transfer fee of around 3.45% to 3.49% of the amount moved. Fee-free balance transfer cards, by comparison, currently offer 0% periods of up to around 12 months.

As an illustration of the potential fee saving: on a £5,000 balance, a 3.49% transfer fee would cost £174.50. Clearing the balance within a shorter, fee-free deal avoids this cost entirely. Whether this trade-off makes sense depends on the size of the balance, the time needed to clear it, and the specific terms available to the individual applicant.

Remember, balance transfer deals can change regularly. To see a list of the top cards available, take a look at our best balance transfer credit cards guide.

Always make sure you can afford repayments.