The historic Old Post Office Building on Pennsylvania Avenue in Washington, D.C. had undergone multiple renovations, and it had been the subject of many schemes to turn a profit by the time Donald Trump and his company, the Trump Organization, leased the property in 2014. The company’s $200-million renovation of the building into the Trump International Hotel has been revealed as a key strategy in Trump’s long avoidance of federal taxes, according to documents acquired by the New York Times.

That reporting found that Trump had paid no federal tax in 10 of the last 15 years, using substantial business losses to offset taxes owed. One of the ways he was able to cancel out some of those taxes was through the use of $9.7 million in business investment credits, including historic preservation tax breaks he applied for to renovate the Old Post Office Building. Built in 1899, the Old Post Office is notable for its ornate Romanesque Revival style and 330-f00t-tall clock tower, making it one of the tallest buildings in the District.

Trump is likely to continue to benefit from tax credits on this project. The tax cuts in question are allowed through the federal Rehabilitation Tax Credit, which grants a 20% credit on “expenditures for the rehabilitation of qualifying buildings,” including those built before 1936 or certified as historic. For the $200 million the Trump Organization spent renovating the Old Post Office Building, Trump will be allowed to cut a total $40 million off his federal taxes between 2016 and 2020. Those credits have presumably been used to bring Trump’s federal tax payment down to just $750 for both 2016 and 2017, the two latest years included in the documents obtained by the New York Times.

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