The Star understands that officials at Bramall Lane accepted what sources describe as “a nominal sum” in return for the 22-year-old, whose move will be confirmed shortly.
But with Slater set to become a free agent at the end of the season, United used that as a lever in negotiations about how much money they would be entitled to if he ever departs East Yorkshire.
Although it is unlikely to be publicly confirmed, City are believed to have accepted United’s request for a 20 percent slice. That entitlement will not be affected by any changes to his contractual situation with Grant McCann’s side.
Slater underwent a medical at City over the weekend, before agreeing personal terms with his new employers earlier today. Hailing from Gleadless and a lifelong United supporter, he has put pen to paper on a two and a half year deal with City possessing an option to extend.
Slater, who joins his former United team mate Tyler Smith at City, emerged as one of McCann’s leading targets of this month’s transfer window after impressing on loan there last season.
He made 34 appearances as City were crowned League One champions but has yet to make a senior appearance this term.
After making his senior debut for United in 2016, Slater also completed placements with Carlisle and Scunthorpe before joining McCann’s squad, where he becomes the first new signing since Acun Ilicali’s takeover.