By Matt Egan, CNN Business

(CNN) -- The expensive 2017 tax law failed to encourage Corporate America to embark on a boom in hiring or job-creating investment.

Just 4% of business economists say their companies accelerated hiring because of the tax overhaul, according to a survey released Monday by the National Association for Business Economics.

And only 10% of business economists said their firms stepped up investments like building factories, buying equipment and purchasing software because of the tax law.

An overwhelming 84% of respondents to the NABE survey found the much-touted legislation failed to move the needle. That's similar to the 81% of respondents who said so in the October survey.

It's the latest sign that the tax law has so far failed to live up to the hype, especially given the enormous price tag. The Congressional Budget Office estimates the tax overhaul will add a whopping $1.9 trillion to the federal budget deficit over the next decade.

"So far, the investment response has been modest and underwhelming," said Owen Zidar, an economics and public affairs professor at Princeton University. "The idea there would be an enormous boom was pretty optimistic."

Buybacks skyrocket

Government statistics show that nonresidential fixed investment spending jumped in the first quarter of 2018, but then decelerated in the next two quarters. Nominal fixed business investment increased just 8.2% through the first three quarters of 2018.

The impact was much more pronounced for Wall Street. Flush with cash, US companies announced a record $1.04 trillion in stock buybacks last year, according to TrimTabs Investment Research. That marked a 71% spike from 2017.

Those generous stock buybacks helped prop up the wobbly US stock market for much of last year. And some worry that the use of excess cash on buybacks instead of job-creating investments will deepen inequality.

"I very much think that this tax cut did not help things from an income and wealth inequality standpoint," said Zidar.

Of course, it has only been one year since the tax law took effect. It's possible that business spending and hiring will accelerate in the future because of the corporate tax cut and repatriation.

White House economic adviser Kevin Hassett defended the tax plan in an interview with CNN last week. He said capital spending was strong in the first half of 2018, though it "started to level off" after that.

"There has been a capital spending boom this year," Hassett said.

Contrast that with a recent Bank of America Merrill Lynch report that was critical of the effects of the tax cuts, which was titled, "The investment boom that wasn't."

Business investment back to pre-tax cut levels

Official statistics on business investment for the fourth quarter are due out later this week, though they will likely be delayed because of lingering effects from the government shutdown.

Whenever they're released, the NABE survey suggests the numbers won't show a boom.

The group said its business investment index declined in January to the weakest level since July 2017 — six months before the tax law took effect. Expectations for the next three quarters also fell sharply.

The tax law was more effective for goods-producing companies, including manufacturers, agriculture, mining and construction. Half of the business economists from those types of firms said investments accelerated because of the cuts. One-fifth of those respondents said hiring and investments were redirected to the United States.

But respondents from other sectors — including transportation, communications, finance and services — saw little impact from the tax law.

Many mainstream economists had been predicting the tax law would fail to inspire a wave of business spending because companies already had plenty of cash and access to cheap capital. If they wanted to invest, they already had the ability to do so.

Worker shortage, uncertainty weigh

Companies that want to hire are also limited by the dwindling pool of qualified workers. Fifty-three percent of respondents to the NABE survey reported a shortage of skilled labor at their company. That's the highest since October 2000, and it comes at a time of very low unemployment.

At the same time, businesses looking to invest in the future have been hit with a surge of uncertainty in recent months. The economic outlook has darkened considerably, especially because of concerns about slowing growth in China. And the US-China trade war makes it difficult for companies to plan for the future. The global economic policy uncertainty index jumped to a record high in December.

Caterpillar, a major bellwether for global growth, reported its biggest earnings miss in a decade Monday. The maker of earth-moving equipment cited "lower demand" in China.

A manufacturing survey conducted by the Dallas Federal Reserve plunged to a multi-year low in December. Although the manufacturing index rebounded in January, some business executives sounded a cautious note on tariffs and the government shutdown.

"We're ridiculously slow on incoming orders," one printing executive said in the survey, which was released Monday.

A machinery manufacturing executive said: "This has been the worst start to the new year in the 44 years I have worked."

The more cautious tone from businesses suggests that deepening uncertainty is overshadowing the benefits from the tax law.