I.R.S. Failed to Police Puerto Rico Tax Break, Whistle-Blower Says

For the past decade, thousands of wealthy Americans have been flocking to Puerto Rico to take advantage of a tax break that can cut their tax bills to zero. For nearly as long, there have been allegations that the benefit enables multimillionaires to avoid paying what they owe when they reap big investment profits.

Now, an Internal Revenue Service insider has accused the agency of failing to police the tax break. Despite a high-profile campaign announced more than three years ago to unearth possible abuse, the agency has audited barely two dozen people and has collected back taxes from none, according to a letter that an agency insider wrote this year to lawmakers and that has been reviewed by The New York Times, as well as interviews with I.R.S. officials.

Senate officials have begun an investigation into the whistle-blower’s allegations about the Puerto Rican tax benefit.

“It’s been three years since the I.R.S. announced its enforcement campaign on this issue,” said Senator Ron Wyden, Democrat of Oregon and chairman of the Senate Finance Committee. “It needs to pick up the pace.”

Hamstrung by decades of budget cuts, the I.R.S. has regularly struggled to crack down on tax avoidance by the wealthiest Americans and large companies. Audits of millionaires have declined more than 80 percent over the past decade, reaching record lows. The agency rarely examines giant private equity firms. And the annual “tax gap” — the difference between taxes that are owed and what is paid — is estimated to be $600 billion.

In an interview, Danny Werfel, the I.R.S. commissioner, said the agency’s enforcement campaign in Puerto Rico, while still in its “early chapters,” was accelerating because of the $80 billion in new funding that the 2022 Inflation Reduction Act provided to the agency.