Economy Plus and upgrades: Travelers with Basic Economy fares are only eligible to purchase Economy Plus seating at check-in and are not eligible to purchase premium cabin upgrades, use their Economy Plus subscription benefits or purchase United Travel Options packages.

On major airlines like United and Delta, the ability to upgrade from Basic Economy to Economy Plus (or Comfort+) in 2026 is strictly regulated and often restricted. On United Airlines, you generally can purchase an Economy Plus seat assignment during the check-in process, even with a Basic Economy ticket, though you will still be subject to other Basic Economy restrictions like "no full-sized carry-on" (unless on international routes). On Delta Air Lines, Basic Economy (E class) tickets are traditionally ineligible for paid or complimentary upgrades to Comfort+, First Class, or Delta One, even for Medallion elite members. American Airlines has a similar policy where "Basic" fares are often ineligible for most upgrades. If you find yourself in Basic Economy and desire more legroom, your best chance is usually to wait until the 24-hour check-in window opens and see if the app offers a "seat buy-up" option. However, for those who value the flexibility of an upgrade, it is always recommended to book "Main Cabin" or higher from the start to ensure eligibility.