Most of Minnesota’s biggest companies have doubled, and in some cases more than tripled, their profit growth this year thanks to reduced taxes under the new federal tax law.

The latest wave of quarterly results, which crested last week, was better than investors and analysts expected. And those already solid results got a boost from the first corporate tax cut since the Reagan administration.

A Star Tribune tally of the nearly two dozen Minnesota-based companies that reported April-to-June results in the last few weeks showed that, for almost all of them, most of their profit growth came from the tax cut. The effect is visible because companies report profits both before and after the effect of income taxes.

The profit before taxes at UnitedHealth Group, Minnesota’s biggest company by revenue and market value, rose 12.5 percent. Its net profit, the bottom line that includes the impact of lower taxes, rose 28 percent.

At 3M, the second most-valuable company based in Minnesota, pretax profit rose 9.7 percent while net profit jumped 17.3 percent. U.S. Bancorp’s pretax profit jumped 5.4 percent but its net profit jumped 16.3 percent.

In the same period a year ago, such differences were smaller. Fastenal, the Winona-based distributor of construction and factory products, saw its net profit grow three times the rate of its pretax profit in the latest quarter. A year ago, the two categories were nearly identical.

In the latest period, Xcel Energy was the only Minnesota company that reported a drop in pretax profit and a jump in net profit. It said it paid $48 million less income tax in the quarter than a year ago, while its net profit rose $38 million. That means, on paper at least, the tax cut accounted for its entire profit.

An Xcel spokesman attributed the profit to favorable weather and margins and said Xcel plans to return savings from the tax cut through rate reductions to customers. “We’re working with our regulators in each state to determine how that will occur,” the spokesman said in a statement.

The outsized effects of tax cuts on corporate results will be limited to this year. Next year’s comparisons will factor in lower taxes.

“Every quarter this year, it will have year-over-year benefit,” Terry Dolan, U.S. Bancorp’s chief financial officer, said of the tax cut. “When we get into next year, that year-over-year benefit will dissipate.”

Investors and analysts are trying to understand the effect of the tax cut in order to make judgments about the broader direction of corporate performance. If profit growth slows next year because the tax-cut effect disappears, they want to understand by how much. Stock prices tend to rise or fall with profits over the long term.

The latest corporate results gave a clearer picture of the impact of the tax cut than did the results for the January-to-March period. Many companies at that time muddied the view by accounting for one-time changes in the value of deferred taxes.

And some of Minnesota’s biggest companies — such as Target Corp., Best Buy Inc. and General Mills Inc. — will report new results later this month or in September.

The new tax law President Donald Trump signed last December reduced the nominal corporate rate to 21 percent from 35 percent. Companies can also immediately deduct new investments, while those with overseas earnings must make plans to bring a portion of them back to the United States.

Minnesota and many other states didn’t change business tax rates, meaning the overall cut to business taxes is not as steep as the 40 percent drop at the federal level.

UnitedHealth, for instance, reported a 21 percent decline in income tax expense to $850 million. For the entire year, the company is on track to pay about $800 million less in income tax than it did in 2017.

Apple Inc., the nation’s largest payer of corporate taxes, reported a 32 percent decline in income tax expense to $1.76 billion. Its 32 percent gain in net income, reported on Tuesday, helped power the company’s market value to over $1 trillion last week, the first publicly traded company in the world to reach that milestone. Not counting the effect of taxes, Apple’s profit rose 17.4 percent in the April-to-June period.

The new law also lowered personal tax rates, though not as steeply. In the first quarter, the U.S. Treasury’s collection of corporate taxes fell nearly 49 percent to $149 billion. Personal tax collection fell by less than a half-percent in the same comparative period.

For the federal government, the new law is leading to a dramatic, rapid increase in its deficit. The White House budget office last month revised its forecasts for the impact of the cuts, adding $100 billion more a year than it previously estimated. The federal deficit is now forecast to balloon over $1 trillion beginning in 2020. Federal debt is projected to rise overall from 78 percent of GDP at the end of 2018 to 96 percent of GDP ($29 trillion) by 2028, the highest level since the end of World War II.

For now, companies have chiefly directed the windfall to shareholders. For instance, Ameriprise, the Minneapolis-based investment advisory firm, said that it paid out its entire quarterly profit to shareholders through dividends and stock buybacks.

Only two companies reported a bigger gain in net profit than in pretax profit. One of them, St. Paul-based Ecolab, noted that one-time charges resulted in a higher tax rate than it had a year ago. Otherwise, its tax rate would have fallen and its net profit would have likely jumped.

The other, Cardiovascular Systems Inc., also of St. Paul, experienced net operating losses and, as a result, does not make a provision for income taxes covered by the new law, an executive said.