For that reason, the IRS monitors compensation by closely-held companies.

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The new investment puts Square among some of the highest-valued closely held technology companies.

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With closely-held (especially family) companies, the IRS has a keen eye for who is getting paid too much.

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They are all decision-makers in their small, closely held family companies, usually having taken over from elderly patriarchs.

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Richard Gliklich, a Harvard professor, runs a profitable, closely-held business called Outcome that develops such prospective databases for big drug companies and organizations like the American Heart Association.

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The companies he controls--Hollinger Inc. and closely held Ravelston -- have just an 18% economic interest in Hollinger International through Class B shares that have ten times the voting rights of common stock.

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