What could be more appealing as a consumer than increased purchasing power and the ability to pay for a large ticket item over time without paying interest? Not much. With credit cards regularly advertising 0% interest rates or interest free days, you may feel tempted to apply whenever an offer like that is presented to you. Before you do though, review these three tips that will help you know exactly what you’re signing on for.

1. Interest free days have their limitations.

If your goal is to use a credit card for long-term financing for a major purchase, you shouldn’t waste your time worrying about the interest free days offered by the issuing bank. Why? Because they won’t last. It’s common for credit cards to offer up to 44 interest free days (like the American Express Gold Ascent card) or up to 55 interest free days (like the Aussie credit card).

Interest free days are great if you plan to pay your balance in full each month, meaning you would never accrue interest, but they’re not as useful for balances you intend to pay off over several months. It’s also important to note that most cards only offer interest free days if you paid off your previous cycle’s balance in full.

2. 0% Interest Rates May Only be Valid on Certain Purchases

Credit card companies may occasionally offer 0% interest rates as an interest-free promotion, but it doesn’t apply to every purchase you make. Instead, the promotional rate applies only when you shop with certain retailers. For example, HSBC credit cards sometimes offer promotional interest-free periods with their partner retailers.

Just keep in mind that promotional rates may come at a cost. For instance, if you use an HSBC Classic credit card at approved retailers during an interest-free promotion, you should be sure to pay off those charges completely before the promotion ends. If you don’t, the remaining balance will be subject to the card’s cash advance interest rate (which is higher than the normal purchase interest rate).

3. 0% Interest Rates May Not be Valid on Purchases at All

Most of the 0% interest rate offers you’re likely to come across are actually not applicable for new purchases. Instead, they’re introductory balance transfer rates. While they can be nice if you want to move your balance from a high interest credit card to a low or no interest credit card without planning to use it for additional purchases, they aren’t right for everyone. If you really need a card for future purchases, it’s generally a better idea to go with one offering a low overall interest rate so you don’t risk being hit with high interest on your new purchases (since many credit card companies force payments to be applied to the lower rate balance transfers first).

By understanding the different types of 0% interest credit card offers and promotions you might come across, you can make better decisions in choosing a credit card that offers you the best deal for your own charging habits.