Standard Sport understands that Middlesbrough will pay £10m up front, with a further £10m potentially due in add-ons for the 21-year-old.
Spurs also retain a 20 per cent sell-on clause and matching rights for Lankshear, who joins Middlesbrough in search of regular first-team minutes.
Lankshear is highly regarded internally at Spurs, but acknowledged they could not offer him the game time he needed to develop.
Standard Sport understands that Spurs are keen to drive greater productivity from their academy, whether through progression to the first team or generating funds that can be invested into Roberto De Zerbi’s squad.
Spurs have already sanctioned the departures of academy players Alfie Devine and Tynan Thompson to Preston and Manchester United, respectively, for a combined fee of around £14m.
Devine enjoyed an excellent season on loan at Preston last term, while Thompson, who is highly regarded in academy circles, was keen to relocate due to family circumstances.
After an aggressive summer of spending, in which they have spent in excess of £200m on new players, Spurs are also determined to become a better selling club and have identified a number of academy players with strong sell-on value.
In negotiating a sell-on clause and matching rights in deals for Lankshear, Thompson and Vuskovic, Spurs believe they have protected themselves on three high-potential players, while generating immediate funds to help finance their rebuild under De Zerbi this summer.