President Donald Trump told Bloomberg News Thursday that he is considering using his executive powers to index capital gains to inflation, a move that would provide a roughly $100 billion tax break to investors over 10 years.

“There are a lot of people that love it and some people that don’t,” Trump said. “But I’m thinking about it very strongly.”

Treasury Secretary Steven Mnuchin said in July that his department was looking into whether the administration could change the rules without congressional approval, simply by changing the definition of “cost” in the relevant section of the tax code, but the White House at the time denied such a move was being considered. It’s still not clear whether the administration has the right to make the change on its own and legal challenges are expected if the president moves ahead with the plan.

Indexing capital gains would allow investors to reduce the taxes they pay on the sale of assets by adjusting the purchase price to take inflation into account, raising the initial price and thereby reducing the profit and tax owed.

The tax break has long been of interest to Wall Street and real estate investors, and Trump’s top economic adviser, National Economic Council chief Larry Kudlow, has promoted the idea for years. Supporters of the proposal sometimes complain that capital gains taxes are applied to “phantom profits” if inflation isn’t taken into account.

Critics point out that the tax break would only worsen the country’s fiscal situation while overwhelmingly benefitting the wealthy. “As a tax cut, indexing capital gains is incredibly tilted towards the wealthy (who hold the most stock, especially outside retirement accounts). 86% of the benefit to the top 1%,” Tyler Evilsizer of the Committee for a Responsible Federal Budget tweeted.

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