Figuring out exactly what the GOP’s tax overhaul means for Corporate America’s bottom line is a tricky business.

Companies from JPMorgan Chase to Colgate Palmolive and General Electric have all cautioned in quarterly earnings reports this month that the presentations they made on benefits and costs from the new law are subject to change as the finer points of provisions, including a reduction in their top rate to 21 percent from 35 percent, become clear.

Assessing what the overhaul means for consumers is an even dicier proposition. The bill was intended, in part, to boost individual spending power, but its simplification of the tax code eliminated popular breaks from the personal exemption to a moving-expenses allowance while boosting the standard deduction, making the net effect difficult to determine.

What people will do with any extra income they gain is a step even further into the unknown.

“We haven’t gone into some deep study of how much does this increase consumer discretionary spend,” Starbucks CEO Kevin Johnson told investors on Thursday afternoon. “I don’t have any models or insight to share with you other than just general intuition: If consumers have more money, then that must be good for us.”’

Profit at the popular coffeehouse chain more than doubled to $2.25 billion in the three months through December, and the Seattle-based company boosted the top of its full-year earnings forecast 8.6 percent to $2.53 a share.

While Wall Street economists haven’t been particularly optimistic about consumer spending, suggesting households are more likely to increase their savings than to buy more, David Yoo, a currency and rates analyst at Bank of America, isn’t so sure.

With AT&T, Apple, and Bank of America awarding bonuses to employees in the wake of the tax bill, pressure is growing on other companies to do the same, he noted.

“Because of peer pressure, a significant share of the corporate tax cut may end up in consumers' wallets boosting household spending,” he said.

That jibes with the assessment that Erin Browne, head of asset allocation and investment solutions at UBS Asset Management, made earlier this year.

“Consumers are going to be more emboldened to spend” with a lower tax rate, she told the Washington Examiner. That should boost revenue for banks, which have more money to lend since they’re paying less to the Internal Revenue Service, she said.

Indeed, JPMorgan, the largest U.S. lender, has already widened a commitment to home loans in low- and moderate-income communities by 25 percent to $50 billion. It also plans to boost home-ownership grants that can be used to cover down payments and closing costs to $2,500.

“While it’s too early to determine the full impact, it appears that tax reform will benefit our customers and help grow the U.S. economy,” Tim Sloan, the CEO of San Francisco-based Wells Fargo told investors earlier this month. “Surveys indicate business confidence has increased.”