Senate Finance Committee Democratic tax staff who reviewed Mehmet Oz’s tax returns said the nominee to run the Centers for Medicare and Medicaid Services avoided paying some Medicare and Social Security taxes over three years.

Dr. Mehmet Oz, the celebrity physician nominated by President Donald Trump to oversee Medicare and Medicaid, appears to have underpaid his U.S. Social Security and Medicare taxes in recent years, according to a memo by Democratic staffers on the Senate Finance Committee.

Trump’s allegiance to Oz was further emphasized on Tuesday when the president announced he was nominating Oz’s son-in-law, John Jovanovic, to head the Export-Import Bank of the United States.