PART 2: There’s nothing more frustrating than going to redeem your miles and finding out that they have all expired. Here’s the latest updates on those rules:

Northwest
WorldPerks miles have no expiration date. However, consistent with the general terms and conditions of the WorldPerks program, Northwest Airlines reserves the right to change the WorldPerks program at any time without notice, including imposition of expiration limits or reactivation fees. If no mileage from any source is posted to a WorldPerks member’s account for three consecutive years, the account is subject to termination, including forfeiture of all accrued mileage.

Southwest
Each credit is valid for 24 months from the date earned. Your Rapid Rewards account will contain only valid credits collected within the immediately preceding 24 consecutive months. If a credit is not applied toward an award within 24 months of the date earned, it will be deleted from your Rapid Rewards account balance.

Spirit
FREE SPIRIT Miles will expire when an account becomes inactive for a period of six months or more. An “inactive” account is one that has less than 2,000 miles credited to it from any source during the preceding six months. Accounts will become inactive during the month-end reporting process, which will be reported to the member on the second business day of each month.

United
Mileage accrued shall only be subject to expiration thirty-six (36) months after the last account activity in the member’s account. In cases where mileage is for any reason removed from an account, as for the redemption of awards, and later returned, the return of the mileage to the account shall not count as account activity. All miles subject to expiration will expire the last day of the thirty-sixth month after the last account activity in the member’s account.

US Airways
Effective Dec 1, active membership status is based on having earned or redeemed miles within a consecutive 18 month period. With the new Mileage Reactivation Policy, Dividend Miles members have an opportunity to reinstate their Dividend Miles accounts to active status for an additional 18 months for a $100 fee. If members do not extend by payment of a $100 fee, the Dividend Miles account will be closed and all miles forfeited. Members who have no account activity for a consecutive 36 month period will have their accounts closed and will forfeit all miles in their accounts. Once forfeited, miles cannot be reinstated. Prior to the above policy changes taking effect, 36 consecutive months of account inactivity will lead to account closure and forfeiture of all miles.