Credit cards customers who are trying to clear their debts are being surprised with further charges even though they may think they have already cleared the balance.

An egg customer and Guardian reader brought the problem to the media attention, the problem can occur when a customer is paying debt carried over from the previous month.

This is what many credit card companies call trailing interest on any negative balance between the issuing of the last statement and the customer paying off the debt.

Some have a minimum fee and if interest does not reach, that amount it will be “topped up” the charge, so borrwers will be repaying no lower than the minimum fee.

Unfair minimum charges

In the case of Egg the minimum is 50p, while at MBNA and Barclays it is 1. For customers with Egg, the internet bank who pay off their debt via direct debit they could incur up to 18 days worth of interest on a balance that they think they have settled in full.

A spokeswoman for Egg, speaking to the Guardian newspaper, said: “Interest is charged on the outstanding balance between our issuing the statement and the payment being made. We request payment via your direct debit 14 days after the statement date.”

Direct debits cannot be called over a weekend so if a customer’s direct debit is due to leave their account on a Saturday or Sunday, we’ll move the payment date to Monday. The longest they’ll go between statement date and paying their account is 16 days – 18 if their payment date falls over the Easter weekend.

The spokeswoman added: “If the interest amounts to less than 50p we top up the charge so it equals that amount. She added that interest would be charged on the outstanding interest and top-up fee.

“All credit card contracts will mention trailing interest in the terms and conditions but more often than not it can be hidden away within the small print of the contract. In Egg’s case the explanation behind the charges has been described as virtually incomprehensible.”

The top-up fee

In the contract it says it will charge, “a top-up fee where the amount of interest charged to your account on any statement is less than 50p and the fee will be the amount required to make the top-up fee plus that interest equal to 50p. Where this applies, your statement will show a 50p minimum finance charge”.

Barclay card mentions on its website that interest is charged until the full date of repayment meaning that you may receive a further interest charge the second month, however there is no mention of the extra 1 pound charge.

Peter Harrison, a credit cards specialist at a leading price comparison website, said too often financial services companies include these wrinkles in their terms and conditions and it is important customers check the details before applying.

He added: “Whilst the sums of money involved are quite small, many customers who want to clear their full balance will, no doubt, find this irritating.”

The extra interest charges are not likely to send customers spiraling back into debt but there is no doubt that many would find it annoying receiving another statement after thinking that the balance had already been paid off.