The Red Devils have been in talks with the Bundesliga champions over a suitable deal for the last two months, but David Moyes' sacking created an obstacle.
However, reports claim the deal has made significant progression after Louis Van Gaal formally replaced the Scot on Monday, with the 'principles of an agreement' now in place.
The Germany midfielder is approaching the final year of his contract and Bayern are looking to sell to avoid Kroos leaving on a free next summer.
Van Gaal is understood to have a £200m budget to play with in the summer, with both the midfield and defence desperately in need of new talent.
Next season United will be without Nemanja Vidic (Inter Milan), Rio Ferdinand (free) and long-term attacker Ryan Giggs, who will take the position on Van Gaal's assistant manager.
Left-back Patrice Evra could also be on his way out of Old Trafford, with Luke Shaw reportedly close to signing as his replacement from Southampton.
Source - Express