As stated, the main benefit of credit cards with 0% interest during their introductory term is that you can use them for multiple purposes while avoiding adding to the balance via monthly interest build-up. And, like other credit cards, they also benefit from purchase protection.
Additionally, some cards may offer rewards or other extras to entice borrowers. Remember that the best interest-free credit cards are not necessarily the ones that offer the longest introductory interest-free term and/or the biggest rewards – the best 0% interest credit card for you might be the one with the lowest or no balance transfer fee.
It's always worth doing some maths before you pick a card to figure out how long you're likely to need to repay the balance. For instance, you may find a 12-month interest-free deal with no balance transfer fee, which is great if you've got a manageable amount of debt, but for more significant amounts, you may need longer to pay it off, in which case you'll want to look for a deal with a longer introductory term.
Just make sure to stay organised, as one of the potential liabilities of these cards is that you may lose track of when your interest-free period ends and not have the debt paid off in time. It could be worth noting the date your introductory term ends in your diary, and budgeting so you pay in enough every month to clear the balance in full by the end – just divide the number of introductory interest-free months by the balance, and voila! Pay that amount off each month and you'll be debt-free by the end of the term.
Given the finite nature of the 0% deals on these cards, you may not want to use them in the long term. Even a card that gives you 30 months to pay off your debt will eventually reach that point, after which the interest rate can ramp up and it might not be as competitive as a low-interest card, for instance.
In a similar vein, if you are only interested in making a few large purchases or clearing previous debt, not both, you'll find that there are longer introductory terms of 0% on purchases or balance transfers to be found if you go for a specific 0% balance transfer or purchase card.
Overall, 0% credit card offers, or any credit card for that matter, should not be used to supplement income or otherwise become something you rely on. While they can be valuable assets for making large emergency purchases where savings fall short, or for helping you get out of credit card or overdraft debt, you don't want to spend the rest of your life transferring debt from one 0% interest credit card to another – it's unsustainable and could be quite costly given that most long-term introductory deals will come with fees.
If you're struggling with credit card debt, consider contacting a debt charity to help you sort out your finances. A 0% interest credit card offers only a temporary solution for those who are seeking extra funds.