MoneySavingExpert founder Martin Lewis says Brits can make money by 'stoozing', the clever use of credit cards - but it is crucial to know what you're doing.
The basic idea behind stoozing is to make money by getting interest on cash credit card firms lend at 0%.
It works like this.
First, take out a credit card with 0% interest.
Do your normal everyday spending using that card.
As you do that, put the cash in your bank account into savings deals paying interest.
Savings rates are finally on the rise following years of pitifully low returns on your cash.
The top savings rate on a fixed account has just breached 5%, while the best-paying easy-access account currently sits at 2.75%.
When the 0% term ends, use some of that cash to pay off the card debt - or transfer it to another 0% card.
Writing on MSE , Lewis said: " While not as lucrative as it used to be, you can still make a pretty penny as long as you know what you're doing. Beware though, if done badly, stoozing can lead to you losing money and significantly lower your credit score."
Lewis said the first steps are to make sure you have no credit card debt, and a good credit score.
It's also important to make sure you're on top of how it all works.
"Do it right and this is risk-free," Lewis said. "Yet stoozing isn't for the forgetful, ill-disciplined or inattentive."
Another thing to get right is to never exceed your credit limit.
This will mean you lose the 0% offer and damage your credit score.
Also make sure you don't overspend - only pay for things you would do normally.
Only making the minimum repayments is also really important.
Lewis said: "Don't try to repay this card in full. Just set up a direct debit to make the minimum monthly repayments, usually around 2.5% of the outstanding balance.
"Don't miss any payments, or you could lose the 0% promo offer, messing up your entire plan."
Another bit of advice is never to withdraw cash on a 0% card.
You will pay interest on cash you take out on these cards, and it can harm your credit score.
Finally, be careful to protect your credit score.
Lewis said lots of credit card applications and high debts - even on 0% interest cards - can harm your credit score, so space your card applications out.
He added: "And if you have a mortgage application or important credit application coming up, a credit card debt (especially if it's maxed out) could affect lenders' affordability checks, so you might need to hold off on stoozing."
