Besides inquiring about why a group didn’t seek IRS approval of its nonprofit status, the questionnaire asks how much money it spent, if any, on political campaigns, including ads to support or oppose candidates.

An IRS spokesman, Anthony Burke, said he couldn’t discuss whether the agency was investigating nonprofits for engaging in political activity. “Under the disclosure provisions of the federal tax law, federal employees cannot disclose tax return information,” he said.

Probe Indicators

All the activity, plus news reports on campaign spending, suggest the question of political involvement by nonprofits has attracted the attention of IRS investigators, said Marcus Owens, who used to oversee nonprofits for the agency. “All the traditional indicators of a project either under way or soon to be under way are there,” he said.

Election lawyer Michael Toner, another former FEC chairman, said he expects the question of whether nonprofits can spend money on political ads without disclosing their donors to wind up in court. He said the IRS may decide to challenge one Democratic-leaning and one Republican-leaning organization and let judges sort it out.

“I do believe test cases are inevitable,” Toner said. “Litigation in the courts is only a matter of time.”

While the nonprofits continue to keep their donors hidden, some of their contributors’ names have become public through IRS filings and voluntary disclosures by corporate contributors.

Donor Disclosures

The Center to Protect Patient Rights, a Phoenix-based nonprofit led by Sean Noble, a Republican consultant linked to billionaire energy executives Charles and David Koch, spent $23 million in 2011. It spread that wealth around; $2.4 million went to the 60-Plus Association, which favors privatizing Social Security and spent $4.6 million on campaigns in 2012. Noble also paid his consulting firms $3 million, its 2011 tax records show.

The Motion Picture Association of America, whose members include News Corp. and the Walt Disney Co., donated $100,000 in 2011 to Grover Norquist’s Americans for Tax Reform, which a year later spent $16 million to elect Republicans, according to the Washington-based Center for Responsive Politics, which tracks campaign donations. An association spokesman, Howard Gantman, declined to comment on its 2011 tax filing and donations.