This article seems to suggest it's mandatory for public companies:
>As Congress chips away at bank regulations established by the 2010 Dodd-Frank law, another part of the measure is exposing the extreme income inequality between bosses and their workers.
>The law requires publicly traded companies to calculate the ratio of their chief executive officer’s compensation to the median pay of the companies’ employees. After a series of delays, firms are finally disclosing their pay ratios in filings with the Securities and Exchange Commission. [0]
Also, do you have to state median pay in such a filing?