The Red Devils are desperate to sign the 21-year-old full-back after the departure of Antonio Valencia, who was released earlier this month after ten years at Old Trafford.
Palace value Wan-Bissaka at £60m but are mindful of the defenders wish to move to the Theatre of Dreams and will not stand in the full-backs way.
However, the Eagles rejected a bid of £50m from United which promised £35m up front and £15m in additional payments based on the clubs success during the defenders time at the club.
Palace were unhappy that United offered just a portion of the fee up front and the Daily Mail claim they want upwards of £45m in a lump sum before allowing Wan-Bissaka to move to the north-west.
Wan-Bissaka is currently on international duty with Englands U21s and will not leave the camp to complete a deal.
Swansea City winger Daniel James remains the clubs only signing so far this summer but Ole Gunnar Solskjaer hopes to sign as many as five more in the next six weeks.