For flights operated by United or United Express, MileagePlus miles typically post to your account within 48 hours after your travel is completed. In 2026, the process is largely automated; as long as your MileagePlus number was on your boarding pass at check-in, the system triggers the credit shortly after the plane lands. For Star Alliance and other partner airlines, the timeframe is longer, usually taking between 5 to 14 days as data must be synced between different carriers. If your miles haven't appeared after 15 days, United allows you to submit a "Request Credit" form online using your ticket number. It is also important to note that miles earned through credit card spend or the MileagePlus X app may take significantly longer—sometimes up to 6 to 8 weeks—to reflect in your account balance depending on your billing cycle and the specific partner's reporting speed.