18.3 PROVISIONAL BALL
18.3a When Provisional Ball Allowed
If a ball might be lost outside a penalty area or be out of bounds, to save time the player may play another ball provisionally. But if the original ball could only be lost in a penalty area a provisional ball is not allowed.
18.3b Announcing Play of Provisional Ball
Before the stroke is made the player must announce that he or she is playing a provisional ball. The player must use the word “provisional” or clearly indicate that he or she is playing the ball provisionally. If a player plays a ball from where the previous stroke was made without announcing, the player’s ball immediately becomes the ball in play under stroke and distance.
18.3c Playing Provisional Ball Until It Becomes the Ball in Play or is Abandoned
The player may continue to play the provisional ball so long as it is played from a spot that is the same distance or farther from the hole that where the original ball is estimated to be.
The provisional ball must be abandoned if the original ball is found on the course, outside a penalty area, before the end of the 3-minute search time and the player must play the original ball as it lies (or declare it unplayable and use one of the unplayable rule options).
If the original ball is found in a penalty area or known or virtually certain to be in a penalty area the player must play the original ball as it lies or take penalty relief under Rule 17.1d. If the player were to make further strokes with the provisional ball he or she would be playing a wrong ball and the general penalty would apply, loss of hole in match play and 2 strokes in stroke play.
Since January 2019 a player may go back and play a Provisional during the 3 minute search period but the timing continues.