Small business owners may want to give bonuses and raises to their staffers now that there’s a new tax law, but many don’t know if they’ll have any wealth to share.

It’s easier for big companies like Walmart and Home Depot to award bonuses because they already know their top tax rate is dropping to 21 percent from 35 percent. Millions of small business owners have far less certainty.

The law gives a break to owners of sole proprietorships, partnerships and small businesses known as S corporations. But while they can deduct 20 percent of their business income, the size of the deduction declines when an individual owner’s taxable income reaches $157,500.

And the IRS still needs to issue regulations on how these owners’ business income is calculated.

We didn’t base any raises or bonuses on the tax situation because, quite frankly, until it actually happens, no one’s sure what’s going to happen,” says Rod Hughes, a vice president at Kimball Hughes Public Relations in Blue Bell, Penn. The company gave its seven full-time employees year-end bonuses last month.

It’s easier for big companies like Walmart and Home Depot to award employees bonuses and raises now that there’s a new tax law because they already know their top tax rate is dropping to 21% from 35% under the old law. But millions of small business owners are far less certain about whether they’ll be able to reward their employees.

“The 20 percent deduction is extremely complex and it’s going to require a complete understanding of how the statute works,”

As a result, giving bonuses or raises in response to a potential tax cut could leave smaller companies vulnerable to a cash flow crisis.