What Is a "PlayStation Network Master Account"? It Doesn't Exist Officially

There is no official "master account" on PlayStation Network. You likely mean one of these:

• Primary Account: The account set as primary on a PS4/PS5—shares games, PS Plus, and content with other users on that console.
• Family Manager: In PlayStation Family Management, the adult account that sets parental controls, spending limits, and playtime for child accounts.
• Misheard term: Slang or confusion from a specific community.

Clarify where you saw the term and what you're trying to achieve for a precise answer.