Credit cards that charge 0% interest on purchases for a set period can cost nothing in interest if the balance is cleared in time. But how they're used decides whether they save money or add to debt. This article looks at both sides.

ClearScore is a credit broker, not a lender.

Credit card borrowing in the UK

According to ClearScore's analysis of Bank of England and ONS data, credit card debt averaged £2,601 per UK household in 2025, close to its 2019 high of £2,606.

Credit card lending accounts for a third of average unsecured credit lending in the UK (excluding student loans), which stands at over £8,300 per household.

Debt can accumulate when consumers use a 0% card to make purchases they can't pay off by the end of the promotional period. And without monthly interest payments to pay, cardholders may be comfortable carrying higher levels of debt than they would normally. If care isn't taken, personal debt levels can creep higher and higher.

Losing Your 0% Interest Promotional Period

You can lose a 0% promotional rate by missing a monthly payment or exceeding the credit limit during the promotional period. On many cards, this can end the 0% period early, so check the terms. If that happens, the card's standard rate applies to the remaining balance. When we checked in October 2026, some of the cards with the longest 0% purchase periods had a Representative 24.9% APR variable, and some cards' standard rates were considerably higher. This may not cover the whole market.

A missed payment can also affect your credit score:

Card providers can still earn money during 0% periods, for example through balance transfer fees and the fees retailers pay when you use the card. They also earn interest from customers who still owe money when the 0% period ends, or who lose the offer early.

Balance Transfer Cards Have the Same Problem

Borrowers face a similar issue with balance transfer cards if they don't make their payments on time or exceed the credit limit. Additionally, cardholders won't get a 0% rate if the balance isn't transferred within a window that's usually 60 or 90 days from account opening.

When a 0% card can be useful

A 0% card can be useful in some situations. For example, a 0% period can spread the cost of a large or unexpected expense, such as a boiler repair, with all of each payment going towards the balance rather than interest. The risk is that the balance isn't cleared by the end of the 0% period, or that new spending adds to it. Working out a monthly payment that clears the balance before the 0% period ends can help. Eligibility and acceptance are decided by each lender and depend on its own criteria and checks. Checking your eligibility does not guarantee that you'll be accepted.