With the swipe of a pen, President Donald Trump gave San Antonio-based Cox Manufacturing an extra $100,000 this year.

That’s a modest gain compared with the billions of dollars in savings other companies are disclosing as they report fourth-quarter earnings in the coming weeks. The Republican tax plan passed by Congress and signed into law just before Christmas has been a windfall for corporations across the U.S., boosting bottom lines as well as incoming business.

AT&T booked a $20 billion paper profit in the fourth quarter on the signing of the tax bill. Health care insurer Aetna Inc. said the new law will add $800 million to its income statement this year. Locally, the tax bill gave San Antonio-based refiner Valero Energy Corp. a $1.9 billion boost in the fourth quarter, the company said Thursday. Defense contractor Lockheed Martin also disclosed a $1.9 billion tax benefit when it released earnings Monday.

For Cox, those savings may give the manufacturer some much-needed relief as it adds staff and equipment necessary to handle the increased orders the company’s been receiving over the last month or so, President Bill Cox said.

“The biggest benefit I think is not the tax savings, but the activity that’s going on. It’s just like crazy,” said Cox, whose company employs 150 and makes machined and other parts. “I had some older machines that we wanted to phase out and I just couldn’t believe how quickly they sold. I’m getting pressure to release them sooner than I wanted to.”

Demand has picked up dramatically since the bill was signed into law, he said. His backlog of orders has grown from six to eight weeks in December to 10 to 12 weeks now, and he’s having to move up construction of a new 8,000-square-foot manufacturing plant by at least a year in order to meet the growth.

“We needed it yesterday,” he said of the new facility.

Cox said his backlog of orders is starting to cost him work. The new factory and equipment — which he hopes to bring online this year — will cost at least $1.5 million, create 15 jobs and would add to his 54,000 square feet of existing manufacturing space.

Paul Hensley, the chief financial officer of San Antonio-based Holt Cat, said demand for the company’s heavy construction machinery started rising in the second half of 2017, which he attributed to the Republican push for tax reform.

“We’re seeing and hearing from our customers that now that the bill is passed, the expectation is that there will be an uptick in business,” Hensley said. “This is a good thing for our customers which will, in turn, be a good thing for Holt Cat in general. We’re looking forward to 2018 — we’re very bullish in the economy, especially in the Texas economy and where we’re going.”

Tom Beck, vice president of operations at Beck Manufacturing International in Converse, said he expects his company, which builds cement mixer bodies that mount on trucks, will see a reduction of close to 10 percent in its tax rate.

The savings will flow into Beck Manufacturing International investments, including an under construction manufacturing site that will double his company’s capacity in Converse, he said.

“That money that we hang on to … that’s absolutely going directly toward the new facility that will employ more people,” Beck said. The full implications of the tax reform bill are still somewhat murky.

Rey Chavez, CEO and president of the San Antonio Manufacturers Association, said “the optimism is great” in the manufacturing community after the passage of the tax reform bill, and said naysayers of the bill “just don’t get it.”

“What they don’t get is that business is what makes things happen,” Chavez said. “Then with a good economy, with a relaxation of some of the regulations … you bet companies are going to invest in their folks.”

Both Beck and Hensley said there are still many unknowns with the tax bill. Clif Teague, a tax advisor in the Houston office of Troy, Michigan-based accounting and advisory firm Doeren Mayhew, said part of that is because it’s one of the largest pieces of tax legislation since President Ronald Reagan’s tax cuts in 1986.

“They don’t know how much the reduction’s going to be, they don’t know any of that stuff,” said Teague. A client recently called the office asking “and they were like, ‘I need to know what the reduction of my taxes are because I’m going to turn around and buy more equipment,’ which would obviously be a good thing.”

Jason Saving, senior research economist at the Federal Reserve Bank of Dallas, said the tax reform not only lowers corporate tax rates but also gives a slightly lower rate to repatriated income from overseas.

Apple said in mid-January that it planned to repatriate a large amount of its money held overseas and would pay a tax bill of $38 billion to do so. At the same time the company said it expects to invest $30 billion in the U.S. over the next five years and create 20,000 jobs.

“The hope is that (the reform) will spur more economic activity here in the United States and to the extent that it does that, Texas’ favorable business climate should leave it fairly well positioned to attract some of this new output, along with some of the jobs that might accompany it,” Saving said.