A minimum credit-card repayment is the smallest amount a cardholder must pay by the due date to keep the account from becoming overdue.

It should not be confused with the amount required to clear the debt quickly.

Minimum repayments are normally calculated as a percentage of the closing balance or a minimum dollar amount, depending on the card’s terms. As the balance falls, the required payment may also become smaller.

That declining repayment can substantially extend the time needed to eliminate the debt. During that period, interest continues to be charged on the remaining balance.

Australia has approximately 14.7 million credit cards carrying about $33 billion in debt, according to figures cited by Moneysmart from the Reserve Bank of Australia.

The cost to an individual cardholder depends on the interest rate, fees, repayments and whether new purchases are added.

A card advertising up to 44 or 55 interest-free days does not necessarily give every purchase that full period.

The interest-free window usually begins at the start of the statement cycle, not on the date of purchase. Access to interest-free days may also depend on paying the statement balance in full.

Cash advances are commonly excluded and may begin attracting interest immediately, together with a cash-advance fee.

Store finance requires similar care. A purchase advertised as {interest free} may still attract establishment, annual, account-keeping or late-payment fees.

When the promotional period ends, interest on the remaining amount can be very high. Moneysmart warns that rates on some interest-free arrangements can reach 26 per cent.

Minimum payments may not clear a promotional purchase before the interest-free period expires. The required repayment should instead be calculated by dividing the entire balance, plus known fees, across the available months.

Cardholders can begin by stopping new discretionary spending on the card and checking the actual purchase interest rate shown on the statement.

Paying a fixed amount greater than the minimum can reduce both the repayment period and total interest. Scheduling the transfer shortly after payday may make the plan easier to maintain.

A balance-transfer offer can reduce interest temporarily, but transfer fees, expiry dates and the rate applied to new spending must be examined carefully. Moving debt without changing spending patterns can result in balances on two cards.

Anyone having difficulty meeting repayments should contact the lender before missing payments. Australian credit providers have hardship processes, and free financial counsellors can help people assess their options.

A credit card can be a convenient payment tool, but convenience becomes expensive when a temporary balance turns into long-term revolving debt.