The Brazilian midfielder has been in good form this season, but his deal at Old Trafford is set to expire at the end of the season.
He is currently the highest earner in the squad, so extending terms on the same wages is unthinkable. United may yet decide to keep him on, but their offer would be reduced, and the player will be weighing up his other options.
United are very pleased with the partnership Casemiro has built with Bruno Fernandes this season, and their schedule has been eased by a lack of European football, meaning the pair have good recovery time between games.
Casemiro, 33, has started eight of their 10 Premier League matches this season.
However, United are starting to look to a rebuild that would see both him and Fernandes eventually phased out - and they want to sign two midfield players in 2026.
Ideally, that process will begin in January, but it is not clear yet whether their targets will be attainable at that stage.
While it is likely United have conversations with Casemiro about staying on and how that could become possible, sources are suggesting they will wait to see how their transfer plans come together - and then deal with his situation properly.
Harry Maguire is in a similar situation to Casemiro, with his contract winding down, but he is expected to sign an extension on reduced terms, and the current understanding is that his case is more of a priority.
United will also look at signing a centre-back in the summer - but want Maguire’s leadership skills to remain as they continue to evolve.
