Bank of Ireland is disputing a Revenue Commissioners' rule that means people who work and bank in Northern Ireland but live in the Republic are being charged Irish Government stamp duty on their sterling-issued credit cards.

The bank, which was the first in the Republic to apply the charge to sterling customers resident here, said it was receiving an increasing number of queries and challenges from customers who believe the charge to be legally unsound.

Eddie Ryan, head of card marketing at Bank of Ireland, said the bank was seeking clarity from the Revenue regarding the application of the €40 charge to its sterling credit card customers.

Guidance notes issued by the Revenue in recent weeks state that everyone who has a billing address in the Republic is liable for stamp duty on bank cards, even if their financial institution is located outside the country.

"All cards regardless of the location of the issuer are liable if the cardholder has an address in the State," according to its website.

This is the second year in which Bank of Ireland has applied the charge.

"We have people calling us saying that the terms and conditions issued with the credit card are applicable to English law and there was no mention of the stamp duty charge, but the Revenue is telling us that they are liable.

"There is a grey area here," said Mr Ryan.

Bank of Ireland said in some cases people with disabilities living in Northern Ireland who had appointed people with addresses in the Republic to handle their affairs were being charged the tax.

It is also seeking clarity from the Revenue on the currency conversion rate that should apply and issues relating to cross-border handling fees.

Mr Ryan said he did not believe that all foreign institutions were levying the stamp duty or were even aware of it.

A spokesman for the Revenue confirmed that anyone who is resident in the State is liable for the stamp duty even if the card-issuing institution is located outside the State. "Some foreign banks are sending in returns," he said.