0% Purchase vs 0% Balance Transfer: Which Card?

Short version: if you already owe money on another card, get a 0% balance transfer card. If you're about to make a big purchase and want to spread the cost interest-free, get a 0% purchase card. They sound interchangeable. They're not. One zeroes the interest on debt you've already run up; the other zeroes it on spending you haven't done yet. Pick the wrong one and you'll either pay a transfer fee for nothing, or watch new purchases rack up interest you thought was paused.

The deciding question is simple: is the money already spent, or not yet?

What each card actually does

A 0% purchase card charges no interest on new spending for a set period. Buy a sofa, a laptop, a flight, whatever, and as long as you clear it before the promo ends, you pay nothing extra. There's usually no fee.

A 0% balance transfer card lets you move an existing debt from another card onto it, then charges no interest on that moved balance for a promo period. Almost always there's a one-off transfer fee, typically around 2-3% of the amount moved as of 2026 (confirm the exact fee on the issuer's site, since it varies by card and offer).

Here's the catch people miss: a balance transfer card does not give you 0% on new purchases unless it separately advertises that. Spend on a transfer card and that spending often starts accruing interest immediately, and your repayments may go to the cheapest debt first. So the two jobs don't overlap as neatly as the marketing suggests.

Side-by-side

Want to see current promo lengths and fees lined up? Our side-by-side compare tool shows them together, and the UK cards hub filters to deals available here.

A worked example

Say you've got £3,000 sitting on an old card at 24.9% APR.

• Balance transfer route. You move the £3,000 to a 24-month 0% transfer card with a 2.5% fee. The fee is £75. You pay £125 a month, clear it inside the promo, and pay £75 total instead of the roughly £700-£800 in interest you'd have racked up leaving it where it was. Net saving: well over £600.
• Purchase card route. A 0% purchase card does nothing here. It only zeroes interest on new spending. Your existing £3,000 keeps charging 24.9% on the old card. You'd save £0 on the debt.

Now flip it. Say instead you've got no debt but need to buy a £3,000 kitchen.

• Purchase card route. Spend the £3,000, pay it off over 18 months interest-free, total cost £3,000. No fee.
• Balance transfer route. Wrong tool. Many won't even let you transfer a fresh purchase, and if you just spend on the transfer card, that spending often isn't covered by the 0% deal and starts charging interest right away.

Same person, same £3,000, opposite answers. It all hinges on whether the money's already gone.

The trade-offs nobody prints on the front of the offer

Balance transfer cards charge you to use them. That ~2-3% fee is real money up front. On a small balance, or one you could clear in a few months anyway, the fee can outweigh the interest saved. Run the sum first. Worth noting: a handful of fee-free transfer deals exist, but they usually come with shorter promo windows.

Purchase cards lull you into forgetting the deadline. Because there's no fee and no obvious downside, it's easy to make the minimum payment and drift. When the 0% promo ends, the regular APR, often above 24% as of 2026, lands on whatever's left. Divide your balance by the number of promo months and pay at least that each month.

Mixing spending and transfers on one card is where people get burned. If a card is set up for transfers and you also spend on it, your monthly payment can be allocated in a way that leaves the expensive new spending sitting there gathering interest. Use one card for one job.

You need the credit score to get the headline deal. The 24-30 month transfer offers and the longest purchase deals go to people with strong credit. If yours is thin or patchy, you may be offered a shorter promo or a higher fee than advertised. Always confirm the actual terms you're approved for, not the marketed ones.

Who should skip both

If you clear your card in full every month and aren't planning a big purchase, neither of these is your card. You'd pay no interest anyway, so a 0% deal saves you nothing. Go for rewards instead, and our annual fee vs no annual fee guide is a better starting point.

Skip both if you're about to apply for a mortgage. Opening new credit and carrying a transferred balance can wobble your score at exactly the wrong moment. And if the underlying issue is overspending, a 0% card is a postponed bill, not a fix, especially the purchase kind, which makes new spending feel free. Sort the spending first.

The practical play

Most people will want one or the other at different times, occasionally both. Shift old debt with a transfer card, float a planned purchase with a purchase card, and don't try to make one card do both jobs. Set a phone reminder two months before either promo ends. To see what's currently on offer here, browse all cards or read how we rate them on the methodology page. If you want the wider UK picture first, start with how to compare UK credit cards.