(Bloomberg) -U.S. utility owners from Duke Energy to NextEra Energy are warning investors that their earnings may take a hit from tax reforms being floated in Washington.

At risk is a provision corporations have enjoyed for years. It gives utilities the right to deduct what can be considerable tax expenses because of the billions of dollars of debt they take out to build massive power projects. Republicans in Congress have proposed ditching this deductible while cutting corporate tax rates. President Donald Trump has suggested a cap.

It’s a move that Morgan Stanley said could cut earnings by as much as 8.5 percent depending on the utility owner, adding that Wall Street has “largely discounted” the idea when it’s too premature to rule out. NextEra said the elimination could contribute to a cut in earnings of 10 cents to 15 cents a share, and Chief Executive Officer James Robo stressed in a call with investors that it’s important for lawmakers proposing tax reforms to “get it right.”

Utilities are particularly dependent on the deduction because of the heavy debt loads they carry to pay for power plants and transmission lines. Its elimination would hit an industry that, facing weakening power demand, is consolidating and seeking financing for multibillion-dollar takeovers. The proposal also threatens to shrink dividends that investors have come to rely on during times of market volatility, and trade group Edison Electric Institute warned it could lead to higher utility bills.

The Trump administration will address questions “when the tax plan is finalized,” White House spokeswoman Kelly Love said by e-mail Feb. 17. The office of Republican House Speaker Paul Ryan, who is pushing a tax-overhaul plan that would kill the deduction, deferred comment to the House Ways and Means Committee.

Emily Schillinger, a spokeswoman for the committee, said utilities would benefit from a lower corporate tax rate and a provision that’d allow them to immediately expense investments under a House plan. Lawmakers understand the “special circumstances of regulated utilities and are working to ensure that the provision on deductibility of interest is crafted in a way that will accommodate those circumstances,” she said.

Should the deduction be eliminated, regulated utilities may be able to recoup expenses from their ratepayers as a cost of service. It’d probably hit their corporate owners the hardest, paring back the cash they have available for dividends, said Jaimin Patel, a credit analyst for Bloomberg Intelligence.

Ryan’s tax plan has drawn intense opposition. Senate Majority Whip John Cornyn has said a key part of the proposal is “on life support” and that lawmakers need to look for other options. While there’s as yet no tax reform bill in Congress, Wall Street analysts including Wolfe Research LLC and Morgan Stanley have pressed utility executives for the potential impact.

Duke Energy said in a call last week that it could see a 5 percent hit to earnings by 2021 from the House Republican tax plan. That assumes a corporate tax rate of 20 percent and that it won’t be able to deduct interest on new and refinanced debt. The loss could approach 7 percent should all interest deductions be eliminated, the company said.

Duke’s Chief Executive officer  Lynn Good described the deduction as “extremely important.” A better tax policy, she said, “would be to retain that interest deductibility and allow us to continue deploying capital and expensing that capital for tax purposes over a longer period.”

PPL and Entergy have also said putting an end to the deduction would affect their earnings.

While earnings could be reduced by about 10 cents a share should the interest deduction be eliminated, PPL might “largely mitigate” the impact by increasing capital spending or shifting more debt to the U.K., which accounts for about half its business, Chief Executive Officer Bill Spence said in a Feb. 1 earnings call.