Tesla, Inc. (TSLA) CEO Elon Musk is a billionaire many times over. But he pays himself a paltry salary to manage the electric company he founded with his own money. This detail and other interesting nuggets of information were made available by the company in a recent filing. (See also: Elon Musk: Success Story.)

According to the filing, Musk's salary is designed to adhere to "current minimum wage requirements under applicable California laws." He earned $45,936, $37,584 and $35,560 as salary in 2016, 2015 and 2014, respectively, and he is expected to earn $49,920 this year. The filing states that Musk has not claimed his salary for those years. (See also: Should Elon Musk Let Someone Else Run Tesla?)

He owns 22 percent of Tesla's publicly traded stock, and much of his wealth is tied to Tesla's performance in the markets. In 2009, he received option awards and equity compensation for his work in the company. Musk sold the options last year because they were due to expire. That sale cost him a tax bill of $593 million. In 2012, the Tesla board approved a compensation committee recommendation for Musk to purchase 5.2 million shares of the company's stock at $31.17, about 5 percent of its total equity at that point of time. 

However, Musk can exercise the options only after he achieves ten milestones related to operations and market capitalization. Among the operational milestones are successful completion of prototypes for the Model X and the Model 3 and aggregate production of 100,00 cars. Tesla stated that Musk has already achieved six out of the ten milestones. (See also: Tesla Model 3 to Be Unveiled in July.)

Musk is a serial entrepreneur, and he plowed cash from successful exits in previous companies into new ventures. He is reported to have earned $22 million from the sale of Zip2, his first car company, and $160 million from Paypal Holdings, Inc.'s (PYPL​) sale to eBay Inc. (EBAY) in 2001. His bets on Tesla and SpaceX, which is privately held, coupled with an expensive divorce almost bankrupted him in 2010. But those days are behind him. The recent surge in Tesla's stock price netted him a cool $1.6 billion within a week. He also owns 54 percent of SpaceX, which is valued at $15 billion by Fidelity. According to the Bloomberg Billionaires Index, Musk has a net worth of $12.9 billion. (See also: How SpaceX Reinvented the Rocket Launch Industry.)

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