ProPublica and The Washington Post wanted to see what impact, if any, the 162(m) limit on deducting executive compensation has had on America’s biggest companies, which generally set the example for Corporate America.

We began with the approach that professor Steven Balsam of Temple University’s Fox School of Business took in a 2012 study for the Economic Policy Institute. He calculated deductible and non-deductible executive compensation for more than 7,000 companies for the year 2010.

We looked at a narrower universe: the 40 members of today’s Standard & Poor’s Nifty Fifty — the 50 S&P 500 companies with the highest stock market value — that reported executive compensation in 1992, the year before the deduction limit took effect.

We asked S&P Global Market Intelligence to add up three categories subject to the limit — salary, bonus and restricted stock that vests over time. S&P separately added all other compensation categories, such as stock options and incentive-based pay, that are fully deductible.

Making the 1992 to 2014 comparison work required some modifications:

• For 1992, S&P recalculated the value of stock options by using an options-valuation formula rather than the numbers companies reported. That is consistent with the 2014 method and makes the values comparable.
• One category of 2014 compensation — the buildup of value in retirement accounts — is not included because the amounts weren’t disclosed in 1992.
• The 2014 numbers omit chief financial officers because they were exempted from the deductibility limit in 2007.

Finally, our numbers don’t include executives’ eventual profits on stock options; we count the value of options when granted, not when executives exercise them.

Our results show that 2014 compensation subject to the deductibility limit grew by about 650 percent per executive from the 1992 level. During this period, the Consumer Price Index rose only about 70 percent.