As more people convert to using contactless payments during the pandemic, a very important financial question arose for Martin Lewis to answer.
It's likely in this period you've been caught out at a store where the business owners will only accept card, but you just have cash.
But since cash is legal tender, does this mean businesses are breaking the rules by only accepting card?
Martin Lewis was asked this question on ITV's The Martin Lewis Money Show, the Mirror reports.
And as always, the finance guru was on hand to answer the question.
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He said: "No, they are not breaking any rules. You are allowed to take card only as long as it's not discriminatory for race or disability or something."
But that brought up the question of what, exactly, a legal tender was.
Martin said: "The legal tender thing is interesting. Legal tender has a strict definition.
"It means if you have a court awarded debt against you, if someone tries to settle and they're paying in legal tender you cannot refuse it. And that's all it means."
He pointed out that in some parts of the country, the only thing that's legal tender is, in fact, coins.
He said: "In Scotland, no notes – neither Bank of Scotland nor Bank of England, are legal tender."
But that doesn't mean they're not legal.
As to whether it's time to switch to a cashless society, Martin had made an excellent point.
Martin said: "I know many people are saying 'why don't we just switch to a cashless society?' – I don't want that, because there are many vulnerable people who need cash.
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And there was good news coming for people who rely on cash, but are finding it harder to get hold of with bank branches closing and ATMs being removed.
He said: "The Government has said that once we leave the EU in January it will change the rules so if you want to get cash out form a supermarket you don't have to buy anything.
"And with the closures of ATMs and bank branches that will be useful."