Any change of payment date will be outlined on the statement
Barclaycard customers who pay their bills in full each month may have their payment date suddenly brought forward, the bank has told the BBC.
The move could put customers at risk of incurring a £20 late payment fee if they do not examine their bills carefully each month.
This revelation comes amid continued criticism of bank profits and not long after the Office of Fair Trading (OFT) investigation into late payment charges.
However, Barclaycard denies it is trying to rake in late penalties, and says it never guarantees customers a fixed payment date each month.
Speaking to BBC Radio 4's Money Box programme, Barclaycard's Ian Barber said any change of date will be explicitly outlined on the customer's statement.
He said Barclaycard was "having to face up to the fact that clearly we are not making as much money out of customers that pay their bill in full as we are out of those that borrow", he said.
He added that the company was "quite open about it... if you pay your bill in full every month you may get a few days less to pay...
"That is the fact of it and we are not going to shy away from that."
Money Box listener Justin from Cambridge contacted the programme after he received his latest bill.
"When I looked at all my previous statements and my February statement, all the payments were required on the 9th of the month. The only one which is not is the December statement which requires payment by the 3 January.
Justin believes Barclaycard has a policy to maximise penalty payments, and he was concerned the company was doing it during the holiday period when banks are often shut.
But Mr Barber denied this and said: "What typically would have happened here is that he would have for a period of time, probably three, four or five months, been regularly paying his bill in full.
"Once we recognise that someone is regularly paying their bill in full, we will shorten the time that they have got to pay a little, and that is what will have happened here."
A simple way to avoid the risk of any late payment charge was, Mr Barber said: "to set a direct debit payment up on the account.
"It is universally good advice to set up a direct debit for at least the minimum amount.
"That way you can make sure you are not going to be hit with any late payment charges, and obviously if you want to pay more on top of that direct debit it is very easy to do so."
BBC Radio 4's Money Box was broadcast on Saturday, 4 February, 2006, at 1204 GMT.
The programme was repeated on Sunday, 5 February, 2006, at 2102 GMT.