Make sure you can use those rewards points

Rewards credit cards are an appealing way to earn back money, gift cards, and even flights by using your credit card. Unfortunately, a decline in available credit, decreasing merchant fees, and narrow profit margins mean that the rewards issued to consumers have dropped as well. Credit card issuers have sometimes resorted to legal means of denying rewards to their cardholders. These are a few of the things to look out for if you have a rewards card, to make sure that you don't miss out on rewards you think you have earned.

Make sure you know how much your rewards points are worth. Card issuers have to have a fixed ratio of dollars to points, but they're free to change the amount of points needed to acquire rewards. Instead of allowing cardholders to exchange points for flights, some credit card companies have made them redeem points for fixed-value travel vouchers, which also puts cardholders at the mercy of shifting airfare prices.

Check to see if there are expiration dates on your points. Many banks issue rewards cards with points that must be used within one to two years. Rolling expiration dates for points can make it even more difficult to redeem them for any significant rewards, since the points must be spent within certain periods, which vary by card.

Is there a spending threshold for your points? If you're an infrequent user of your credit card, you may not be able to earn many points at all. Some credit cards only allow cardholders to accumulate or redeem points after spending a certain amount, sometimes up to $1,000, per year.

Be on the lookout for earnings caps. This is a fairly common tactic used by credit card issuers, which limits the points you can acquire or the rewards you can obtain in a given time period. These are often found on cards that have high point-to-dollar ratios, since they encourage people to apply for new cards, while preventing avid rewards-seekers from redeeming too many points.

-Seth Berger