United and Getafe are expected to finalise an agreement for Saiz in the next 24 hours after the Elland Road club bowed to a request from the midfielder to quit English football and return to his home country.
Saiz travelled to Madrid over the weekend following a series discussions over his future in the lead-up to Leeds’ game at Bolton Wanderers on Saturday.
The 27-year-old informed the club that he was unhappy in England and keen to go back to Spain after 18 months with United.
Leeds moved quickly to open talks with Getafe over a move which will see Saiz join the La Liga side on loan until the end of this season.
That transfer should become permanent for a fee of around £6m next summer, ending Saiz’s time in Yorkshire. His outing against QPR nine days ago, Saiz’s 53rd in the Championship, will be his last for Leeds.
United have accepted a loan offer over an immediate cash sale to avoid a scenario where an unhappy Saiz remains at Thorp Arch while other options are explored.
The former Real Madrid trainee, who spent the 2012-13 season with Getafe, has started just one match since the end of October and Leeds claimed a 1-0 win at Bolton without him on Saturday. Marcelo Bielsa’s side are a point clear at the top of the Championship.