A recently discovered detail could potentially disrupt negotiations over President Donald Trump’s significant legislative proposal, as it poses a serious risk to certain businesses in New York and other states with high taxes.

The controversy centers around a measure that would negate state regulations allowing various partnerships to benefit from the 2017 tax reform, which capped the State and Local Tax deduction for personal income taxes at $10,000.

Many business pay taxes under the personal code, not the corporate one.

And where the 2017 reforms gave almost every individual filer a net tax cut, it hit some partnerships harder.

Consequently, approximately 40 states implemented complex regulations to protect these businesses from severe consequences; New York’s version is known as the Pass-Through Entity Tax, or PTET.

But if Congress kills the PTET, it’ll mean these NY biz would collectively have to pay $5 billion to $6 billion more in federal taxes, calculates the Empire Center’s E.J. McMahon.

And partnerships in New York City might be especially hard-hit, if the new federal rule also removes the deduction for the city’s 4% unincorporated business tax.

The net effect would be to boost the company’s tax bill by something like 50% — a hit that will send those that can leave fleeing to Florida, Tennessee or other low-tax states.

And that includes many of the most profitable firms, and thus the ones that most bolster the local economy

Ironically, this move may have been how the tax-writing wonks sought to replace the federal revenue lost by increasing the SALT limit from $10,000 to $30,000 to help out individual filers in high-tax states — but that doesn’t do much for the business filers (nor would even a $60,000 “cap”).

Of course, the root problem here is the insane tax rates imposed by Albany, Trenton, Sacramento and so on.

But until those state governments see the light, it’s the individual and business taxpayers who suffer.

The partnerships that would get slammed are only now waking up to the peril, and giving their representatives in Congress an earful.

So stay tuned for yet more high-stakes drama as Republicans work to enact the Trump agenda.