If you’ve been stockpiling frequent flyer miles or other reward points earned with credit cards, better use them before you lose them.

That’s the word from Robert McKinley, who has been following the credit card industry for more than 20 years as founder of CardTrak.com, based in Naples, Fla. 

To offset losses due to consumers defaulting on their card debt, issuers are already jacking up interest rates and fees, not to mention cutting or freezing credit limits. Next, card companies are likely to trim their costs by reducing the value of rewards or even eliminating the programs entirely with little advance warning, according to McKinley.

“Rewards programs cut into profits, and issuers can make changes in them faster than they can with other card terms, so you may suddenly get a letter saying that you need more points for airline seats or that the rewards program is over, effective immediately,” McKinley says.

Another way you can lose reward points is by making late payments, which will also trigger penalty fees,  typically $39 these days. Penalty fees were one source of card company revenue that actually rose last year as the economy took a nosedive. According to industry consultant R.K. Hammer, card issuers' penalty fee income jumped to $19 billion in 2008, up 5 percent from the previous year. Penalty fees in 2009 are predicted to increase further, to a record $20.5 billion. 

So if you’re planning to take a trip to use up some reward miles, make sure you’ve got your credit card payment set on autopay or in the mail before you leave and don't inadvertently pay a price for cashing in those "free" miles. —Andrea Rock