The corporate tax cuts signed into law by President Donald Trump in 2017 significantly increased investment in the U.S. economy and slightly increased worker compensation, but they did not come close to paying for themselves as promised, The New York Times reported.

The corporate tax cuts resulting from the Tax Cuts and Jobs Act (TCJA) are adding more than $100 billion a year to America’s $34 trillion-and-growing national debt, according to a detailed report by the National Bureau of Economic Research. The report was written by researchers from Princeton University, the University of Chicago, Harvard University and the U.S. Treasury Department.

They also found that the wage gains resulting from the tax cuts were “an order of magnitude below” what Trump officials predicted: about $750 per worker per year on average over the long run, compared to promises of $4,000 to $9,000 per worker.

The study is the first to use broad data from corporate tax filings to draw conclusions about the law, the Times reported. Its authors found that partisan arguments in favor and against the tax cuts were wrong in part; Democrats claimed they rewarded only shareholders and did not help the economy, while Republicans called them a cost-free boon to the middle class.

“The evidence that taxes matter for investment really is there,” Gabriel Chodorow-Reich, a Harvard economist and one of the paper’s authors, told the Times. “And the evidence that corporate tax cuts are expensive also is there. They’re both just features of the data.”

In conducting their research, the authors drew on anonymous data from 12,000 corporate tax returns from before and after the law passed, finding that corporations that benefited from the law increased investment significantly more than those that did not.

They found that both the reduction in the corporate tax rate and the ability to write off all domestic investments immediately spurred more investment. But they found that the immediate expensing was a far more efficient incentive and came at a lower cost to taxpayers, as it rewarded firms for making new investments instead of reducing their taxes on profits earned from investments made long ago.

“It has a bigger bang for the buck,” another author, Erik Zwick of the University of Chicago, told the Times.

The researchers also found that reducing taxes on income earned abroad increased multinational firms’ investments overseas as well as in the United States.

Total additional investment helped to increase the size of the economy by about 0.1 percentage points a year, which translates to a long-run increase in average wages of about $750, they found, which was well below Trump administration forecasts.

The study suggests a possible compromise for lawmakers looking to spur investment efficiently without further increasing the budget deficit, Zwick told the Times: Extend the expensing provision, but pay for it by raising the corporate rate.