ort, Rep. Sander Levin of Michigan, the senior Ways and Means Democrat, called it a "witch hunt" to punish supporters of Obama's law. The dual nature of AARP has raised questions before. The business side of the organization runs money-making enterprises. The most lucrative involves "branding" a series of health insurance plans for seniors and older adults with the AARP name, akin to the Good Housekeeping seal of approval. The public policy side is a civic organization that acts as a watchdog over Social Security and Medicare, representing 37million members and consumers generally. Boards overseeing the business and tax-exempt social policy branches have overlapping directors. Royalties from licensing the use of AARP's name earned $657 million for the organization in 2009, or nearly half its total revenue, according to publicly available records. Health insurance plans accounted for most of that. "During this investigation it became very clear that despite its privileged tax-exempt status, in many cases, AARP represents a for-profit entity, in fact, an insurance company," Boustany said. Hammond responded that AARP has a good relationship with the IRS, and does not anticipate any problems. Citing taxpayer confidentiality laws, the IRS declined to comment. In the past, AARP angered Democrats when it supported former President George W. Bush in creating a Medicare prescription drug benefit offered through private insurers rather than through the government. After that program was launched, the plan sponsored by AARP became the most popular in the nation. Now Republicans are the ones raising questions. The lawmakers' report, 18 months in the making, looked at publicly available federal and state records on AARP's business. An IRS specialist on tax-exempt organizations assisted with the research and helped interpret results. The lawmakers say AARP refused to provide some documentation. The report found that insurance sales are AARP's single largest source of revenue, far eclipsing member dues. AARP-brand offerings are the market leaders for Medicare prescription coverage, private Medicare Advantage insurance plans, and Medigap supplemental coverage that fills in benefit gaps in traditional Medicare. UnitedHealthcare, which operates the AARP plans, paid the organization $427 million in 2009 for the use of its name, according to the report. The report said an important difference in how AARP makes money on the various insurance plans creates an opportunity for profit from the health care overhaul. AARP gets a flat rate for the use of its name on prescription drug plans and Medicare Advantage plans. However, it receives a per-member fee for every Medigap enrollee, 4.95 percent of the premium. AARP collects the full premium directly before remitting United's share. That allows it to invest the money and earn interest. It also requires that seniors purchasing an AARP Medigap plan become dues-paying members of the organization. The arrangement is potentially more lucrative than a flat rate. That's where the new health care law comes in, the report said. Medicare Advantage membership is projected to decline under the law because of cuts in federal payments to the private insurers. Previously the com