With the England international having struggled for game time at Old Trafford, United were happy for the 28-year-old to make the temporary switch to the London Stadium.
Lingard has enjoyed a productive start to life with the Hammers, contributing three goals from his opening four Premier League appearances.
However, while West Ham would like to retain the services of Lingard in the long term, The Times says that United still hold the cards regarding the playmaker's future.
The report claims that United refused to hand West Ham the option of triggering a permanent deal at the end of the season, despite Lingard's future at the club being in considerable doubt.
United recently activated a 12-month option in Lingard's contract keeping him at his boyhood club until 2022.