Wan-Bissaka will see himself earn around £80,000 a week.
That's a significant rise from £10,000 a week that he has been pocketing at Selhurst Park.
After the medical, Wan-Bissaka will go for holiday and then join his new team-mates ahead of pre-season tour.
Wan-Bissaka set to be United's second summer signing
Wan-Bissaka is set to be United's second signing of the summer. Earlier, Ole Gunnar Solskjaer's side bought winger Daniel James from Swansea City for £15m. The 21-year-old youngster signed a five-year contract.James had a stunning 2018-19 season and scored five goals in 38 appearances.
Wan-Bissaka set to become fifth costliest signing for United
According to Sky Sports, Wan-Bissaka will cost United £45m plus £5m based on add-ons.
The England U-21 defender will be United's fifth most expensive signing of all-time.
Paul Pogba (£89m), Romelu Lukaku (£76m), Angel Di Maria (£59.7m) and Fred (£52m) are above Wan-Bissaka in this list.
The promising player featured 39 times across all competitions for Palace last season.
United's trust in youth the way forward?
Signing two promising youngsters is a positive step taken by United.