(CNN) -- Anti-war activist Cindy Sheehan, who is being sued in California by the federal government, said she has a duty to not pay taxes because her son died in what she called an "immoral" war.
An Internal Revenue Service officer, in a federal filing Tuesday in Sacramento, said Sheehan has refused to provide financial information for the 2005 and 2006 tax years. The filing asks the court to order Sheehan to comply.
Sheehan, of Vacaville, told CNN affiliate KXTV she has not paid federal incomes taxes since 2004 -- and has not disguised the fact.
"I feel like I gave my son to this country in an illegal and immoral war. I'll never get him back," Sheehan said. "And, so, if they can give me my son back, then I'll pay my taxes. And that's not going to happen."
Sheehan drew national attention when she camped outside then-President George W. Bush's home in Crawford, Texas, throughout August 2005 to demand a meeting with the president over her son's death.
Casey Sheehan, a 24-year-old Army specialist, was killed in an April 2004 battle in Baghdad. His death prompted his mother to found Gold Star Families for Peace.
In 2011, Sheehan raised questions about whether U.S. special forces had indeed killed al Qaeda leader Osama bin Laden.
"It's not that I don't believe (President Barack) Obama about Osama because he's Obama, I don't believe him because he is just one in along (sic) line of butt-naked emperors," Sheehan wrote on a blog.
Her anti-war protests included a 2010 stint on the grounds of the Washington Monument.