A ball on the putting green may be cleaned when lifted under Rule 16-1b. Elsewhere, a ball may be cleaned when lifted except when it has been lifted:

1. To determine if it is unfit for play (Rule 5-3);
2. For identification (Rule 12-2), in which case it may be cleaned only to the extent necessary for identification; or
3. Because it is interfering with or assisting play (Rule 22).

If a player cleans his ball during play of a hole except as provided in this Rule, he shall incur a penalty of one stroke and the ball, if lifted, shall be replaced.

If a player who is required to replace a ball fails to do so, he shall incur the penalty for breach of Rule 20-3a, but no additional penalty under Rule 21 shall be applied.

Exception: If a player incurs a penalty for failing to act in accordance with Rule 5-3, 12-2 or 22, no additional penalty under Rule 21 shall be applied.