Douglas Bruce, the Colorado Springs anti-tax activist, was indicted today for failing to pay taxes, according to the state Attorney General’s office.

A grand jury indicted Bruce, best known as the author of the Taxpayers Bill of Rights or TABOR, for not paying taxes on income he earned in 2005, 2006 and 2007, according to an Attorney General’s news release. For instance, the indictment alleges that Bruce filed a false state tax return for 2005, when he reported no taxable income. In fact, Bruce earned hundreds of thousands of dollars that year through interest income and the payoff to him of a real estate loan, the indictment charges.

Bruce did not file state tax returns for 2006 or 2007, according to the indictment, even though he continued to earn income through interest and as an El Paso County commissioner.

The indictment also accuses Bruce of funneling his income into the accounts of Active Citizens Together, a nonprofit group he created, without reporting it. In conversations with state Revenue Department officials, Bruce described those deposits as donations or loans.

If convicted of the charges, Bruce could face up to six years in prison and a $500,000 fine.

Colorado Springs police officers arrested Bruce Friday at a post office in Colorado Springs. He was booked into the El Paso County Jail on a $10,000 bond, which he later posted. A phone call to his house went unreturned.

Bruce has a level of notoriety in Colorado matched by few activists or politicians. In addition to authoring TABOR — one of the most consequential ballot initiatives in state history — he also served as a state representative for one session, during which he became the first Colorado legislator ever punished with censure after kicking a news photographer on the session’s opening day.

Last year, he resisted repeated attempts — by activists, judges and the state attorney general — to testify about his role in writing and funding three tax-cutting ballot measures. Those initiatives failed at the polls, but a judge later fined Active Citizens Together $11,300 for not reporting what it spent to put the initiatives on the ballot.

On Tuesday, Bruce lost a bid for an at-large Colorado Springs City Council seat, finishing ninth out of 16 candidates. The top 5 were elected to the Council.