Flathead-area Rep. Tom Millett faces an unpaid income tax bill totaling at least $427,000 after repeated court losses in a years-long dispute with the federal government about whether he failed to pay his full income tax bill between 2004 and 2017.

Millett failed to file an income tax return in every year between 2004 and 2012 except 2010, according to court filings. That period includes at least one year, 2009, when the IRS says he earned more than $100,000.

Representing himself in the legal dispute, Millett has argued that, as he interprets the U.S. tax code, his earnings were exempt from taxation because he believes income is technically taxable only for residents of federal districts such as Washington, D.C. He has also argued that the IRS failed to properly notify him about his tax debts.

To date, that logic has failed to persuade a Montana-based federal judge, Donald Molloy, who ruled against him in a series of orders in 2022 and 2023, and a panel of judges at the 9th U.S. Circuit Court of Appeals, which declined to take up his case in late July. Millett said in emails to Montana Free Press this week that he is considering a further appeal to the U.S. Supreme Court.

Molloy also upheld a federal tax lien on a property that Millett is part owner of in Marion.

“I will abide by the final decision of the courts,” Millett wrote to MTFP.

“I believe in exercising my 5th Amendment protected right to due process and for holding everyone, even the federal government, accountable to following the law,” he continued.

Millett also told MTFP that he is current on his post-2018 tax bills and that he has paid state income taxes. State income taxes are the largest revenue source for the state budget, which is passed by the state Legislature.

Millett, a first-term Republican who represents Libby and rural areas west of Kalispell, also said he plans to seek re-election in 2026.