McClaren signed a three-year deal in June after being appointed as the club's new deal.
But the Daily Mail today claim that a top-eight finish in the Premier League – or a cup win – would trigger a long extension to his contract at the club, which last won a major trophy in 1969.
With Newcastle fighting relegation – McClaren's side are 18th in the table – only a victory in the FA Cup final in May would see him land the extra five years this season.
United take on Watford at Vicarage Road on Saturday in the third round of the competition.
Former manager Alan Pardew was handed an eight-year deal by owner Mike Ashley after guiding the club to a fifth-placed finish in 2012.