The United States will qualify for the second round of the tournament if they draw or win against Germany in Recife in a game which starts at mid-day Eastern Time.
In the style of a 'doctor's note', Klinsmann addresses employers and asks them to forgive their staff for their absence.
The letter was distributed on social networks by the U.S. Soccer.
"I understand that this absence may reduce the productivity of your workplace, but I can assure you that it is for an important cause," wrote Klinsmann.
"The #USMNT (U.S. Men's National Team) has a critical World Cup game vs Germany and we will need the full support of the nation if we are to advance to the next round.
"By the way, you should act like a good leader and take the day off as well. Go USA! Signed Jurgen Klinsmann, Head Coach, U.S. National team".
Interest in Klinsmann's team and the World Cup in general has reached new heights in the States with record television audiences and widespread media coverage.
Viewing parties at bars and public areas have taken off as a popular of watching games.