The Beverly Hills tax attorney tapped by President Donald Trump to lead the Internal Revenue Service has represented a number of high profile clients fighting that very agency, including one of Contra Costa County’s most high-profile families — the Seenos.

Charles Rettig has spent the last five years representing a number of Seeno family members after they sued the federal government, hoping to recoup some of the more than $159 million in delinquent federal income taxes paid by the family, and it appears he was successful in two of the cases.

The Seeno family runs one of the largest home building operations in the East Bay. In 2008, the IRS sent Albert Seeno Jr., his son Albert Seeno III and brother Thomas Seeno tax-delinquency notices for more than $159 million in federal income taxes from 2000 to 2006, claiming the family used a now-outlawed, controversial tax shelter strategy to underpay their personal returns, according to court documents. The Seeno trio, along with Thomas Seeno’s two sons-in-law and other wealthy businessmen, have sued the IRS to get reimbursed for most of the back taxes they had to pay.

With Rettig’s help, according to a Feb. 2 court status update, the United States announced it had accepted settlement offers from Seeno Jr. and Seeno III.

Details of the deal have not been made public, and requests for comment from the Seeno’s attorney and the federal tax attorney representing the United States were not immediately returned Tuesday.

Rettig helped the Seenos file the lawsuit in 2013, along with 15 related cases, all involving the now-outlawed SC2 tax shelter program.

The entire operation came under scrutiny in 2003 when the U.S. Senate investigated a handful of tax-shelter programs, including SC2, and found them “dubious.” KPMG, the accounting firm that created the shelter, was fined $456 million and 19 accounting firm executives received indictments, with three sentenced to prison.

Senate investigators estimated shelters cost the federal government $1.4 billion in taxes. In 2004, the IRS ruled that it considered SC2 an abusive tax-avoidance transaction.

The controversial tax strategy allowed the Seenos and others to “donate” large amounts of stock in their company to a charity, with an agreement to return it later. The temporary “parking” of the taxable income allowed the Seenos and others to avoid paying taxes on it, instead paying a much-lower capital gains tax on the income at a later date, according to court documents.

To make it work, a Los Angeles police and fire pension fund was recruited to accept the “donations” and pocketed millions of dollars for its role.

In 2005, Rettig defended the tax shelter to the Los Angeles Times: “The SC2 transaction is not the poster child for abusive tax shelters that the government would portray. The tax result may be highly objectionable to the IRS. But as a technical matter, many knowledgeable practitioners are convinced it will be upheld in litigation.”

Last month, Trump pegged Rettig to become the IRS commissioner. His nomination is pending at the U.S. Senate Finance Committee.

As part of his nomination process, Rettig lists Seeno Jr. and the Albert D. Seeno Construction Company on his disclosure form as sources of compensation exceeding $5,000 in a year. The Estate of Michael Jackson is also on that list of clients.

In February 2016, Rettig, writing as a Forbes contributor, commented on the controversy over whether Trump should release his tax returns.

“Would any experienced tax lawyer representing Trump in an IRS audit advise him to publicly release his tax returns during the audit?” Rettig wrote. “Absolutely not.

“He likely pays taxes at a lesser rate than many of us given the nature of his real estate and similar investments being subjected to lower tax rates than salaries earned by the rest of us. Certainly, his tax professionals have not advised him to overpay his taxes,” he wrote.

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Seeno Jr.’s brother Thomas Seeno, and six other linked cases, are still in negotiations in the tax shelter case. The next status hearing is scheduled for May 3.