The credit cards with the longest interest-free periods

There's a lot more to interest-free days than you might think.

This seemingly straightforward credit card perk has a few traps that people can fall into.

First up, don't assume your card has interest-free days. There are five cards on the market that have none, which means you'll be paying interest from the very first day.

Before you sign up to a credit card, find out how many interest-free days you have and what that means in terms of your billing cycle.

Lenders say you have "up to" a certain number of days for a reason - but that's actually the maximum number of days you get, not the minimum.

Confused? Here's an example.

Say you have a 55-day interest-free card. On day one of your statement cycle you'll get 55 days but on day 30 you'll only get 25. Unsurprisingly, there's an even bigger catch: if you have money owing on your card, you don't get any interest-free days at all.

There are plenty of other ways you can inadvertently void your interest-free days.

If you take money out from an ATM, it's a cash advance that gets charged interest straight away. Balance transfers are also likely to cost you your interest-free days, so don't roll over your debt and then hit the shops with a brand new card thinking it will be fine.

One of the biggest traps customers fall into is repaying the minimum balance thinking that's enough. Not only will you'll lose your interest-free days, you'll also pay exorbitant interest rates of up to 24.99%. If you are someone who is likely to forget to pay your bill, try to keep a positive balance on your card. That way it's nearly impossible to get into trouble.

Some banks offer up to 62 days interest free, giving customers up to two months to pay off their card. This kind of perk sounds handy but it's incredibly easy to lose track of where you're at. If you do opt for one of these cards, diarise when your bill is due and make sure you have the funds to pay it off.

Interest-free days:

• Number of cards with 0 days interest free: 5
• Number of cards with 55 days or more interest free: 139
• Number of cards with 62 days interest free: 9
• Average number of days interest free: 52
• Range: 0 to 62

Cards with 62 days interest free:

• Beyond Bank Low Rate Visa Credit Card
• Coles Low Rate Mastercard/Platinum Mastercard
• Coles No Annual Fee Mastercard/Platinum Mastercard
• Coles Rewards Mastercard/Platinum Mastercard
• Latitude Financial Services, GO Mastercard
• People's Choice Credit Union, Visa Credit Card

Get stories like this in our newsletters.