The Red Devils hold an option to extend their manager's deal by 12 months before it runs out in 2019.
Bar a major dip in form, that means United can trigger the extension on Mourinho's £10m-a-year contract or agree a new deal entirely.
Since Sir Alex Ferguson's retirement in 2013, United have failed to mount a serious title challenge, finishing seventh, fourth, fifth and sixth in the Premier League.
The club believe Mourinho is the man to throw them back into title contention and want him as part of a long-term plan for success.
After bringing in the likes of Paul Pogba and Romelu Lukaku, United are also happy to follow the Portuguese tactician's transfer strategy, with Valencia playmaker Carlos Soler, Sweden winger Emil Forsberg, Antoine Griezmann and Gareth Bale all being monitored.