The Spaniard’s deal was set to expire in June but the club triggered a one-year extension in November.
De Gea is understood to be content at Old Trafford, particularly after the team’s mid-season revival under Ole Gunnar Solskjaer.
The Telegraph reported in February that both parties are working towards a new long-term, lucrative deal – but the 28-year-old’s wages have become a sticking point.
Currently earning £240,000 a week, De Gea believes he should be rewarded a deal worth double that total, rivalling the pay package of Alexis Sanchez.
It is a stipulation De Gea and his agent, Jorge Mendes, have remained firm on, and one which United are hesitant to meet.
United white-collars may have their hand forced, however.
The shot-stopper was very close to joining Los Blancos in 2015 but the transfer fell through on deadline day.
The 13-time European Champions signed Thibaut Courtois from Chelsea on a six-year deal last August for £35m, but the Belgian has not nailed down the spot between the sticks.
Zinedine Zidane returned as manager in the Spanish capital this week and will be leveraged a hefty warchest to regain elite status in Europe, after the club were knocked out by Ajax in the Champions League round of 16.
Recruitment has already begun under the Frenchman, with Porto centre-back Eder Militao agreeing a £42.7m deal to switch in July.
The reported £75m put away for De Gea would break the world-record transfer fee paid for a goalkeeper, edging out the £71m which brought Kepa Arrizabalaga to Chelsea last summer.
United officials are not currently concerned about outside interest and believe they will agree terms with De Gea before the end of the season.