Wan-Bissaka has made 190 competitive appearances since joining Man United from Crystal Palace in the summer of 2019.
While he is regarded as one of the Premier League's best one-on-one defenders, Wan-Bissaka has struggled to produce the attacking output expected by top full-backs in the modern game.
Man United are keen to recruit a more attack-minded right-back to provide competition to Portugal international Diogo Dalot.
As a result, the Red Devils are looking to free up space in their squad by offloading Wan-Bissaka, who is now in the final 12 months of his contract.
West Ham make progress in Wan-Bissaka pursuit
While West Ham United have emerged as the frontrunners to sign Wan-Bissaka, a recent report suggested that the move was thrown into doubt due to the player's wage demands.
However, according to journalist Florian Plettenburg, the Hammers have now agreed personal terms with Wan-Bissaka over a five-year contract.
Having been given a boost in their pursuit, West Ham will now work hard to agree a transfer fee with the Red Devils.
The Hammers have reportedly made an £10m offer which is below Man United's £18m asking price, ensuring there is still work to be done in negotiations.
Why are both clubs open to Wan-Bissaka switch?
Having seen Ben Johnson depart, West Ham are left with Vladimir Coufal as their sole natural right-back ahead of Julen Lopetegui's first season in charge.
The Hammers have seemingly identified Wan-Bissaka as someone who could be their first-choice right-back after they initially showed interest in Bayern Munich's Noussair Mazraoui.
However, Man United quickly moved to the front of the queue for the Morocco international, forcing West Ham to consider other options.
The Hammers could actually help facilitate Mazraoui's move to Old Trafford, with the Red Devils waiting to offload Wan-Bissaka before they can look to finalise a deal for the Bayern defender.