How Credit Card Interest Really Works

Why your balance is not going down

If you pay only the minimum each month, most of your payment covers interest — not the original balance. That is why people search “why is my balance not going down” even though they never miss a payment.

Credit card interest is usually calculated daily on your outstanding balance. Each day, interest is added; when you pay less than the interest charged that month, the balance grows.

How daily interest is calculated

UK card issuers quote APR (Annual Percentage Rate). The daily rate is roughly APR ÷ 365. On a £3,000 balance at 24% APR, daily interest ≈ £3,000 × 0.24 ÷ 365 ≈ £1.97 per day — about £59 per month before you reduce any capital.

Interest compounds: you pay interest on interest if the balance is not cleared. That is why high-APR balances feel impossible to shift on minimum payments.

Minimum payments: the slow trap

Minimum payments are often around 1–3% of balance plus interest, or a fixed floor (e.g. £5–£25). They keep your account in good standing but can stretch repayment over decades.

Example: £2,000 at 22% APR with £50/month might take years and cost hundreds in interest. If £50 barely exceeds monthly interest, the balance never falls — our calculator flags when payments do not cover interest.

The interest-free period

If you pay the full statement balance by the due date, you typically avoid purchase interest entirely. Once you carry a balance, interest usually applies to new purchases immediately — check your terms.

0% promotional periods pause interest for a set time but often charge high rates afterwards if balance remains.

Cash advances and higher rates

Withdrawing cash on a credit card often triggers immediate interest (no grace period) plus a fee. Cash advance APR can exceed purchase APR.

Balance transfers

0% balance transfer cards can pause interest for 12–24 months. Transfer fees (often 3–4%) apply. You must meet minimum payments and clear or move the balance before the promotional rate ends.

How to pay less interest

Pay more than the minimum — even £20 extra per month materially shortens payoff time. Pay highest-APR cards first (avalanche method) or smallest balances first for motivation (snowball method).

Avoid new spending on cards you are trying to clear. Consider a fixed monthly payment you can sustain.

If you are struggling

Contact your lender early — they may offer payment plans. Free help is available from StepChange, National Debtline and Citizens Advice. See our resources page for links.

Model your payoff time

Use our Credit Card Interest Calculator UK: enter balance, APR and monthly payment to see months to clear and total interest. Compare scenarios before changing your payment amount.