Holiday shopping? Don't forget that extra cash back.

When you’re using your credit card to buy holiday gifts, it’s easy to forget those cash-back bonuses that some card issuers offer.

Extra cash on rotating categories. Some bank-issued credit cards offer extra cash back of 5 percent or so on merchant categories that change every three months. So your card may give you additional cash when you shop at electronics and drug stores during one quarter and at home improvement centers and discount stores the next.

For example, from Oct. 1 through Dec. 31, the Chase Freedom card is offering 5 percent cash back on a combined limit of $1,500 in purchases from Amazon.com and select department stores. Discover is offering 5 percent back on most online purchases now through Dec. 31. It also has a $1,500 combined limit.

So make sure you know which merchant categories are eligible during this holiday season. Unfortunately, card issuers typically require you to sign up each quarter, or you won’t get the benefit. One trick to remember the current eligible categories is to write them on a piece of paper and tape them to the back of your card. Otherwise, there’s a good chance that while you’re in that shopping frenzy, you’ll forget.

Check out Consumer Reports' Holiday & Gift Guide for more money tips, ideas for a healthy holiday, and gift suggestions.

Discounts from affiliated merchants. Some credit card issuers give you extra cash back if you buy through their websites at affiliated merchants. For example, at the Citi Bonus Cash Center, cardholders can earn unlimited cash back averaging 5 percent at hundreds of participating retailers, with some merchants giving you as much as double that. There are many free shipping deals as well. But as with rotating bonus categories, it's easy to forget about these offers. So write a reminder on a sticky note and attach it to your computer and maybe make a second one for your refrigerator, wallet, or anywhere else you'll notice it.

—Anthony Giorgianni