Tex. Ins. Code § 4053.002

An agent licensed under Subchapter E, Chapter 981, Subchapters B-E or I, Chapter 4051, or Chapter 4056 is not a managing general agent unless the agent accepts 50 percent or more of the agent's total annual business or does $500,000 or more of total annual business as measured by premium volume, whichever amount is less, from insurance policies produced and sold by other agents.