USGA Rules and Decisions:
Under 9-2(b), loss of hole, however in this case, hole is halved
9-2/6
Player Reporting Wrong Score Causes Opponent with Chance for Half to Pick Up Ball
Q.In match play, A holed out and stated to B, his opponent, that he had scored a 4. B, having played four strokes, picked up assuming he had lost the hole. A then realized that he had scored a 5. He immediately told B. What is the ruling?
A.A gave wrong information as to the number of strokes taken and, under the principle of Rule 9-2, A would normally lose the hole. However, since A had holed out for no worse than a half, the hole was halved - see Rule 2-2.