Keeping track of expiring miles is quite frankly a task I'm not good at keeping up with. And it just got tougher. By year's end, most of the airlines will have reduced the amount of months in which inactive mileage accounts expire. These airlines historically adopted a three year (36 month) rule for expiring miles. Recently US Airways dropped to 18 months, Delta to 24, and American and United to 18.

The airlines are also trying to get these pesky inactive miles off their balance sheets to improve their numbers. For instance, United alone had over 508.8 billion unused miles at the end of 2006. They estimate that 870.5 billion will go unused and expire under the new policies. In terms that matter to us, that's nearly 3 million (at 25,000 miles per ticket) free domestic U.S. flights!

Keeping this in mind, it's important to keep those accounts active and save your miles. It only takes SOME SORT of program activity within the 18 (or 24 in Delta's case) months to keep the account from disappearing. Here are some good ideas:

• Take a paid flight on the carrier or an alliance partner of the carrier
• Redeem those miles! Heck, even if it's for a magazine subscription...
• Use a credit card that awards frequent flier points - even purchasing a pack of gum will suffice
• Use miles at a hotel stay
• Rent a car and have the miles credited to your program (be prepared for an additional fee for some carriers)
• Download the Mile Manager tool in our "Tools" section to help manage your programs.