Originally Posted by
no1cub17
But they (along with DL) also only let you upgrade higher fare buckets, which often are at least $350 more than the cheapest bucket, with no guarantee of an upgrade. I can live with the co-pay if that means you can still upgrade the cheapest fare bucket.
Miles & Copay upgrades on United can be used on any fare class. You're thinking of Global Premier Upgrades, which have to be used on W fare or above for long haul intl flights.
My wish is also for the copay charge to be waived when upgrading a flight with miles, especially for Elites.