The two clubs have been in negotiations for some time now, but Spurs chairman Daniel Levy wants to strike a cheaper deal for the England Under 21 star.
Boro boss Chris Wilder says he expects the player back for pre-season training in a fortnight. He said: “If nothing happens with Djed, then he's our player, and he'll be back for pre-season.
"He obviously sees his future away from here, and he had a brilliant season last season. We're expecting that deal to happen, but if it doesn't, then he's our player.
"We're not going to allow anyone to take advantage of us. We're prepared to pay fair numbers, but we're not going to be silly, and we're certainly not going to be giving our players away for a fee we don't think is right."