The USTA Regulations prohibit a player from being entered, when entries close, in two or more tournaments if any part of the tournaments overlap, unless each Tournament Committee understands the situation and concurs in writing. There are two exceptions to this rule on the national junior level.
Both the USTA National Championships and the USTA National Opens allow for a player to enter more than one age division, however, it is important to understand the consequences of this decision.
If you want to play in one of these tournaments, but aren't sure if you will get in, you may enter up to two different age divisions. When selection is done, players are selected for the oldest age division first.
If you are selected into the older age division entered, you will not be selected into the younger division.
If you are not selected into the older division, you will only be considered for selection into the younger division and you will only be eligible to be an alternate in the younger division.