The bill lowered the top tax rate from 39.6 percent to 37 percent. But it was far more generous to the wealthy who, like the president, structure their businesses to pay tax on a so-called pass-through basis. They gained a whopping 20 percent deduction on their income.

While the bill placed limits on wealthy taxpayers claiming this deduction, there was a special carve-out for real estate — the main source of Mr. Trump’s wealth. As a result, the bill cut the top rate on people who, like the president, own pass-through businesses in the real estate industry all the way to 29.5 percent.

And that’s just the start. The 2017 bill also repealed the “like-kind exchange” rule for all property except, you guessed it, real estate. This rule allows the wealthy to indefinitely defer paying tax on capital gains when they change their investment portfolio but do not liquidate.

One positive feature of the 2017 tax law was a new limit on the deductibility of interest payments, which helps reduce the tax bias in favor of debt-financed investment. One might assume that Mr. Trump, as the self-proclaimed “king of debt,” would be hurt financially by such a limit. But in another happy twist for the Trump family, real estate developers can elect out of the limitation entirely.

Subsequent Treasury regulations have also been great news for real estate developers. For example, the bill’s Opportunity Zone provision dramatically reduces or eliminates capital gains taxes due on funds invested in designated areas. According to the president, his daughter Ivanka pushed very hard for this provision. But while purportedly designed to stimulate investment in poor areas, these regulations inexplicably gutted some provisions restricting the tax perk to new business activity. These generous tax breaks are now going to the toniest neighborhoods in some cities and prime beachfront property in New Jersey, benefiting Mr. Trump’s son-in-law in the process.

All of this raises the question of whether the president steered the 2017 tax bill and subsequent regulations in directions that personally benefited him and his family. Moreover, because Mr. Trump is the only president for at least 40 years not to liquidate his business assets or put them in a blind trust, concerns about his financial conflicts of interest are uniquely heightened.