The bulk of the fee is set to be paid up front and Maguire is open to the move.
The Hammers saw a £20m offer knocked back by the Red Devils last month for the England international.
But they have improved their bid, with the two clubs reaching an agreement in the region of £30m.
Personal terms are also not thought to be an issue between the east London outfit and the 30-year-old.
Despite work needed regarding the details of Maguire’s Old Trafford departure, West Ham are increasingly confident about landing their No.1 centre-back target.
Should the transfer go through, United will have taken a £50m loss, having signed Maguire for £80m from Leicester in 2019.
Maguire had been reluctant to depart the Theatre of Dreams having initially wanted to try and win back his place under Erik ten Hag.
But after being stripped as the club’s captain, it became clear that he was not in the Dutchman’s long-term plans.
And with Euro 2024 coming up at the end of the season, Maguire knows he must be playing regular football to earn his spot in Gareth Southgate’s squad.
