To be sure, temporary or not, the tax breaks have been a boon for small businesses. The National Federation of Independent Business said at least 10 percent of small business owners have ranked taxes as their most important problem nearly every month since 1973 when the group began polling Main Street.

But now, in the midst of the first tax season since the law went effect, Main Street advocates are cheering parts of the overhaul but are also arguing that the law didn't go far enough. Tax breaks enacted to help small businesses aren't permanent, and that's made it difficult for business owners to make long-term decisions. Some would like to see Congress move to make temporary tax breaks permanent.

And Pol's not alone. Taxes have long been a sore spot for small businesses, which is one of the reasons optimism soared as President Donald Trump took office and began the process of overhauling the law.

Pol said she also utilized Section 179 expensing to write off a major purchase of new semitrailers — six in all, totaling $1 million. Taxes were often a top issue prior to reform, she said.

"We're estimating around up to $40,000," Pol said. "By utilizing that, we gave our employees raises, knowing that was going to help us for taxes this year."

The entrepreneur runs four small companies across Iowa, including Mowbility Sales & Service, which sells agricultural equipment, and Geetings Inc., a trucking and warehousing business. Pol said she saw a drop in her overall tax burden this year thanks to the qualified business deduction, a change made to the individual tax code, available for pass-through entities . Her savings look substantial.

In the wake of the new law, however, taxes have not taken the top spot since December 2017, being outweighed by concerned about skilled labor and government red tape.

Views on the benefits of tax reform have also waned somewhat, despite the boost it's given to sentiment, according to data from CNBC and SurveyMonkey. In the first quarter of 2018, 46 percent of small business owners said that government tax policy would have a positive effect on their business over the next year. By the fourth quarter, that number fell to 31 percent — the lowest recorded in the two years since polling began.

The qualified business deduction of 20 percent that Pol and other pass-through businesses used to lower their tax bill this year expires in 2025, unless Congress acts to make this permanent. The deduction is capped at the first $157,000 for individual filers and $315,000 for joint filers and is limited to certain types of businesses over that threshold. Corporations also got a permanent 21 percent tax rate, while the owners of pass-through businesses could face rates of up to 29.6 percent — so the parity between big and small businesses that small business groups have long fought for did not exactly come to fruition.

"We got some groundwork laid for parity for small companies but didn't actually get there. So big corporations that make millions of dollars are actually seeing their tax rates at a lower level than many small businesses that are pass-throughs," said Todd McCracken, president and CEO of the National Small Business Association. "And we don't think that's fair. We want permanence — that's been our mantra since the beginning — simplify, bring us parity and give us some level of stability and permanence."

And for that reason, Pol admits that while her optimism is high now, she has concerns about the future. She recently expanded one of her businesses with a new 40,000-square-foot warehouse and said business in the area is strong. But planning is tough without permanent tax cuts — in fact she recently went to testify on Capitol Hill on behalf of the NFIB on the positive impact of the new law on her business. While there, Pol also urged Congress to make the provisions she and other businesses benefited from a permanent part of the tax code.

"Business in this area seems to really be booming. Down the line, what I am hearing and seeing, is that people are getting a little concerned because of the provisions not being permanent. I think there's great optimism for at least the next two, three years here. And after that, I think people will start getting a little more concerned," Pol said.