Carrick has made 376 appearances for United and has become an integral part of Van Gaal???s set-up since returning from injury.
The midfielder was injured during pre-season and missed the start of the campaign before returning for the Manchester derby, which saw United lose 1-0 to Manchester City at the Etihad Stadium on November 2.
Carrick suffered a further muscular rupture before returning to action. He scored for United in their most recent match against Tottenham, the club he moved from in 2006 to join the ranks at Old Trafford.
Van Gaal has tipped Carrick for management in the future but was keen to tie the 33-year-old to a new deal.
The Manchester United boss added: “He is important because he can read the game as a player on the pitch, so he can cope during the game. He can improve that I think.
“He is a midfielder than can play the ball forwards and that I like because our aim is always passing the ball more forward than sideways or backwards and he is a player than can do that and he is my second captain. He is an important player for my selection.
“I think every player has their own contribution. We don???t have to exaggerate things. Wayne Rooney is my first captain and Michael Carrick is my second captain. That says enough how I value these players.”