What are restrictions for junior tennis players on number of senior tournaments?

Question

Recently in a discussion I have heard that young players can only enter a limited number of senior tournaments. The number depends on the age of the player. (This information was mentioned in an interview with a coach of a girls' singles grand-slam champion, when discussing her transition into competing at senior level.) I would like to know more about these limits.

What are limits for the number of senior tournaments a junior player can enter. Do they depend on age? Are they different for men/women?

Answer 1

ATP World Tour / Challenger

According to section 7 of the ATP Rulebook, the following restrictions apply for male players:

7.02 Entries

A. Gender / Age Limitation

The ATP will use the age of a player on the first (1st) day of the qualifying competition. Male players age sixteen (16) or older are not limited in the number of tournaments they may enter. Players under the age of sixteen (16) are subject to the following entry restrictions in ATP World Tour or ATP Challenger Tour tournaments (includes entry as a wildcard):

1. Male players under the age of fourteen (14) shall not be eligible for entry into any ATP World Tour or ATP Challenger Tour tournament.
2. Male players aged fourteen (14) shall be eligible for entry into a maximum of eight (8) ATP World Tour or ATP Challenger Tour tournaments.
3. Male players aged fifteen (15) shall be eligible for entry into a maximum of twelve (12) ATP World Tour and ATP Challenger Tour tournaments.

Answer 2

WTA/ITF - Women Competitions

For more details you can look into 2015 WTA Official Rulebook (Internet Archive). Briefly summarized it says in the section XV. Age eligibility and player development that:

• Players under 14 cannot enter tournaments on WTA or ITF Women's Circuit.
• Above 14 players can play in Fed Cup.
• 14 years old player can play at 8 ITF Women's Circuit tournaments. (This limit is on the number of tournaments between her 14th and 15th birthday.)
• 15 years old player can play 10 tournaments (and WTA Finals or WTA Elite Trophy if she qualifies).
• 16 years old player can play 12 tournaments (and WTA Finals or WTA Elite Trophy if she qualifies).
• 17 years old player can play 16 tournaments (and WTA Finals or WTA Elite Trophy if she qualifies).
• For players that reached 18 years there is no limit on the number of professional tournaments.

ITF - Junior Competitions

There are also limits on the number of junior tournaments a player may enter. Again, for more details see 2014 Junior Circuit Regulations (Internet Archive).

I will reproduce here the table from that document (Appendix G: ITF junior circuit age eligibility rule) which gives an overview.

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|   Age | Number of Tournaments permitted                           |
|   18  | Unrestricted                                              |
|   17  | Unrestricted                                              |
|   16  | 25                                                        |
|   15  | 16 (and 4 additional tournaments for players in Top 20)   |
|   14  | 14 (and 4 additional tournaments for players in Top 20)   |
|   13  | 10 (and 4 additional tournaments for players in Top 50)   |
| 11/12 | 0                                                         |
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