Almost every adult in the UK could receive a payout of up to £300 from Mastercard after a court ruling paved the way for a £14bn class action lawsuit.
It may sound too good to be true but how could this happen?
Former financial ombudsman Walter Merricks claims 46 million people paid higher prices in shops over a 16-year period than they should have because of excessive card fees.
His proposed class action was thrown out in July 2017 by a specialist tribunal, which ruled the claim was "not suitable to be brought in collective proceedings".
But the Court of Appeal has ruled the Competition Appeal Tribunal (CAT) must reconsider the class action against the firm as CAT had applied the wrong legal tests two years ago.
Could you receive a payout?
It doesn't matter how much you spent or what you purchased - if you were over 16, a resident in the UK for at least three months between 1992 and 2008 and bought an item or service from a UK business that accepted Mastercard, you could be owed money.
How much could you receive?
If the £14bn was awarded and divided between the 46 million eligible people the payout would amount to £300 each.
How has Mastercard responded?
Mastercard said it continued to "disagree fundamentally" with the claim and is seeking permission to appeal against the ruling to the Supreme Court.
A Mastercard spokeswoman said: "This decision is not a final ruling and the proposed claim is not approved to move forward, rather the court has simply said a rehearing on certain issues should happen.
"Mastercard continues to disagree fundamentally with the basis of the claim and we believe UK consumers receive real value from the security, convenience and consumer protection of our payment services."