For the new SAT that is coming out in March 2016. What is the highest possible total score?
The maximum score is a 1600. There are two sections: Math and Evidence-Based Reading and Writing. The maximum Math score (made up of your scores on both the calculator and non-calculator sections) is 800, and the maximum Evidence-Based Reading and Writing score (made up of your scores on the Reading and Writing & Language sections) is also 800.
The essay on the March-2016-and-later SAT is scored separately from the rest of the test, because it is now optional. You also no longer receive one essay score - instead, you receive three scores, each out of 8, on Reading, Analysis, and Writing.