The good news for 2026 travelers is that United MileagePlus miles never expire. In 2019, United Airlines permanently removed the expiration policy, meaning as long as your account remains open, your miles are safe regardless of how long it has been since your last flight. This is a significant advantage over other airlines that require "activity" every 18 to 24 months. However, while the miles don't expire, your account could technically be closed if it is deemed "inactive" for a very long period (usually several years of zero logins or activity), or if you violate the program's terms. To keep your account "healthy" in 2026, it is a good idea to perform at least one transaction every year. This doesn't have to be a flight; you can earn miles by using a United co-branded credit card, shopping through the MileagePlus Shopping portal, dining at a participating restaurant via the MileagePlus Dining program, or even by donating a small number of miles to a charity. By engaging with the program even once a year, you ensure that your account remains active and your hard-earned miles are ready whenever you decide to take your next big trip.