Most people have seen this call at one time or another in youth baseball leagues. The batter squares to bunt and as he does so, he steps on home plate, and bunts the ball while he is stepping on home plate. The umpire may call him out and state that he is out because he was stepping on home plate while making contact with the ball. Is that the correct call? The answer depends on what league you play in. Most leagues begin their rules with Major league baseball rules and then add or modify them. If the rule isn't specifically addressed in the modification, then most of the time the major league rule applies.
Major League Rules
In Major league baseball, there is no rule that specifically calls out a batter for stepping on home plate while making contact with the ball. So a Major league umpire would not call out the batter in the example above for stepping on home plate while bunting the ball. He should call him out if his foot is completely out of the batter's box when he makes contact with the ball. Rules Rule 6.06 - a batter is out for illegal action when -
a) He hits a ball with one or both feet on the ground entirely outside the batter's box.
So in theory a player could be touching home plate with his toes and touching the batter's box with his heel and he would be legally considered in the batter's box and would not be called out.
Check your league rule book to see if they have made an ammendment to this rule or added a rule for stepping on the plate. Some leagues have added to the rule stating "He hits a ball with one or both feet on the ground entirely outside the batter's box or touching home plate."
So what, when will this ever happen? Probably never, but the reason I put this example in was so that you understand the rule about what is considered in and out of the box as it applies to the batter. In rule 6.03 it states "The batter's legal position shall be with both feet within the batter's box. APPROVED RULING: The lines defining the box are within the batter's box." What that means is that the batter is considered to be in the batters box as long as part or each foot is touching the lines or is within the lines. I've seen coaches complain when a batter is back in the box and the foot is partially out of the box. But as long as part of their foot is touching the line, they are in the box.
Why do you think pro players wipe out that back line in the first inning of each game? They want to gain an inch or two if they can. No line, no out call for being out of the box.
In youth baseball, bunting is the most obvious situation where a player would run into trouble of stepping outside the box. Another potential problem is when a player wants to move as far up in the box as possible when facing a slow pitcher. If he places his front foot on the front line of the batter's box, he is fine as he prepares to hit. But if his stride takes his foot completely out of the batter's box, then he should be called out on contact. Rule 6.06 a. states that the batter is out in this situation whether the ball is fair or foul.