You might have noticed many credit card companies, including Discover, JPMorgan Chase and Citibank, now offer quarterly bonus categories as part of their product line. These are a great way to earn cash back and other rewards points and because the card networks make the most of the calendar year, it’s easy to save money in retail department stores in late summer, when parents are buying school clothes and travel rewards and online shopping opportunities around the holidays. But to make the most of them, you have to know what to do – and what not to do.

These bonus spending categories change each quarter and they typically offer generous savings opportunities, including things like 5% cash back, triple travel rewards and even bigger savings when you shop through the credit card company’s online mall.

Here’s the kicker: you must register every quarter to ensure you’re eligible for the additional savings or cash back. If you don’t, you could be missing out on the very reason you chose that credit card.

Not only that, but because the offers change every three months, you credit card company can make changes at any time, so you’ll want to pay attention to any kind of updates or revisions to the categories.

Also, the caps will vary from one credit card company to another. For instance, if you make $2,000 worth of qualifying purchases in any quarter and your cap is at $1,000, you’ll only earn the bonus points, cash or rewards up to the $1,000 cap.

The remaining $1,000 will be limited to whatever the standard rates are. And again, be sure to check the guidelines frequently as they change on a dime.

You may wonder why some banks and credit card companies offer such generous rewards opportunities. The answer is simple: they know you’re likely carrying another credit card (or two or three) and they want to be sure you choose their card over the competition that’s sharing space in your wallet.

This is a great way to keep those swipes coming in their favor. The rotation provides new reasons, every three months, for you to choose their credit card. It’s an impressive marketing effort and one that’s hit its target once you understand how popular they’ve become.

Also, there’s been some talk of even more credit card companies and banks jumping into the bonus category game.

By using the caps, the card companies ensure they’re not giving too much away. It keeps them profitable while keeping their customers happy, too. It’s entirely likely that most customers won’t earn more than $100 per quarter, regardless of which credit card they’re using that offers the rotating categories.

While these credit card offers bring with them an incentive, it could be too much of a good thing for some. Consumers might justify overspending by convincing themselves they’re earning cash back and in essence, they’re getting the products at reduced costs.

That, of course, can be dangerous especially if it’s money they wouldn’t have spent were they using cash. Forget to register and even the most justified reasons become moot. There are a lot of dynamics that play into these kinds of credit card offers.

These offers also come with other restrictions. For instance, Chase offers in its fourth quarterly bonus cash back for airline travel, but you have to book your flights and make your hotel reservations directly from the airline and hotel websites.

Also, if you don’t find any reference to say, spending caps, you should keep looking or call the customer service phone number on the site to ensure you’re not missing something. Assume nothing.

Set up reminders at the end of the final month before a category expires so that you can go ahead and register for the next quarter. By setting alerts on your smartphone or email calendar, you’re assured of not missing out on any opportunity.

While you’re shopping online, get into the habit of going through the card’s website. That one simple step can be the difference between 25% and 45% off that sweater you’ve been eyeing or that vacation that’s long overdue.

And don’t hone in on the bonus categories just because you’re earning a bit more cash back. These should be treated as nice little surprises you discover as you’re checking out – not as an incentive to hit the mall because you’re earning 5% cash back.

Finally, in order to really make the most of these bonus categories, your goal should be to pay your balances off each month. This results in not having to pay interest, which adds to the savings, regardless of whether it’s due to the standard rewards or the bonus rewards.

Do you take advantage of bonus categories your credit card offers? If so, how do you make the most out of the rotating categories? Have you run into any problems? Share your story and let us know your thoughts.