NBA rules state that each team is given six timeouts each during the course of a 48-minute game, with one 20-second timeout allowed per half and each overtime period.
Each team is also limited to no more than three timeouts in the fourth quarter. If a team has two or three full timeouts left with two minutes remaining in the fourth quarter, one of those timeouts will be changed to a 20-second timeout and the other will remain a full timeout.
Should the game reach overtime, each team will have two 60-second timeouts. If a team has two full timeouts remaining when the overtime session reaches the 2:00 mark, one of the timeouts will be changed to a 20-second timeout.
Any player that is in the game or a coach can request a timeout, but only when the ball is dead or is controlled by a player on the team making the timeout request.