The case will have an impact on many thousands of claims
The latest stage of the battle over overdraft charges will take place later this month, with a date now set for a judgement by the Supreme Court.
The judgement on Wednesday 25 November will give a final ruling on whether the Office of Fair Trading has the power to decide if the charges are fair or not.
Banks involved in the legal battle appealed against earlier decisions by the High Court and the Appeal Court.
However, it could be some time until people know if they are to be refunded.
The Supreme Court judges, in one of the first judgements made since the creation of the new court, will announce whether to uphold the right of the OFT to regulate bank charges.
THE STORY SO FAR...
Nearly a million people have claimed for the return of their unauthorised overdraft charges but their cases are on hold
If the banks win their latest appeal, these people are unlikely to get any money back
If the banks lose, then the legal arguments should move on to a key stage - a case to determine whether these charges were fair or not
Only then will people have a clearer picture as to whether billions of pounds will be handed back to customers
Seven banks and one building society want to overturn two previous rulings that would let the OFT investigate their overdraft fees.
In a three-day appeal in the House of Lords in June, the banks argued they would receive a "deluge of litigation" if the decision was made against them.
If the courts upheld the right of the OFT to scrutinise bank charges, then the charges might be deemed unenforceable for a time period dating all the way back to the 1990s, their legal team argued.
The OFT said it was concerned about the high cost of bank charges and the way in which they operated.
All new claims against banks were effectively suspended in July 2007 when the OFT and the banks agreed to stage the test case to see if the overdraft charges were legal or not.