The AP reviewed 990 tax returns for nonprofit groups that were made publicly available and posted on both the Guidestar and the Foundation Center websites, searching between 2009 and 2011 under the terms "tea party," "patriot" and other terms frequently used by tea party groups. Several tea party groups also made their tax returns available to the AP. The returns detailed revenues and expenses for the groups, as well as other details. Donors' identifies, however, are shielded from disclosure under federal tax code provisions.

Only 21 of the 93 groups reported annual gross receipts higher than $25,000 between 2009 and 2011, according to the AP review. The $25,000 figure is a threshold for the IRS because an organization's financial strength and revenue sources are important factors in determining its tax-exempt status. Nonprofit groups reporting less than $25,000 a year are allowed to file a short-form, postcard tax return instead of a detailed filing — one indication of a low-budget operation.

The median income for all the groups was just $16,700 a year. That figure includes several tea party organizations that boasted million-dollar budgets and a cluster of others with more than $100,000 in annual revenues. The well-funded activist groups were led by the Georgia-based Tea Party Patriots Inc., the nation's biggest tea party group, which started out with more than $700,000 in annual revenues in 2009 and grew to $20.2 million annually in 2012.