Understanding Alaska Air Companion Fare Expiration rules is essential to avoiding losing out on savings. The fare must be used within a year of its issuance, so you should arrange your trip before then. Travel, however, can be planned for a later time. If you purchase round-trip economy tickets on the Alaska Airlines website, you can apply the companion fare. Check your Mileage Plan account for information if you're unclear about when it expires. Making a plan in advance guarantees that you maximize this beneficial benefit.