On April 20, 2006 CRS released Tax-Exempt Organizations: Political Activity Restrictions and Disclosure Requirements, which explains the Internal Revenue Code (IRC) limitations on lobbying and campaign intervention by groups exempt under IRC 501(c)(3) (charities, religious organizations and private foundations), 501(c)(4) (social welfare organizations), 501(c)(5) (labor unions), 501(c)(6) (trade associations) and 527 political committees. 501(c)(3) Organizations The report explains that lobbying by charities is limited to no more than a substantial part of their activities. It notes that Congress created a "safe harbor" to help define the amount of permissible lobbying in Section 501(h) of the tax code, since "substantial lobbying" has never been clearly defined. Attempts to influence candidate elections are prohibited. It notes that the tax code or Internal Revenue Service (IRS) regulations "do not offer much insight as to what activities are prohibited." While endorsements and campaign contributions are clearly not allowed, the report notes that "501(c)(3) organizations are allowed to conduct certain election-related activities so long as the activities are non-partisan." The report provides examples of factors that indicated whether an activity is biased in support of or opposition to a candidate. These include the following:

• Voter guides may show bias by rating candidates, not giving them equal treatment or comparing their positions with those of the organization. Questionnaires sent to candidates must give all candidates an opportunity to respond to clear and unbiased questions. Answers should not be edited.
• Public forums are unbiased when all qualified candidates are invited and given equal opportunity to present their views on a broad range of issues in response to a nonpartisan panel. A moderator should state that the views expressed are not those of the sponsoring organization, and the group does not support or oppose any candidate.
• Inviting candidates to speak is permissible, as long as all candidates have the same opportunity. There should be no fundraising during such events. When candidates are invited in some other capacity, such as a public official, there should be no reference to the election.
• Voter registration drives are considered nonpartisan if they do "not indicate any preference for a candidate or party." The services must be available regardless of a voter's political preferences.
• Issue advocacy is not considered electoral activity, since "501(c)(3) organizations may take positions on policy and legislative issues…" However, the report notes that "the line between issue advocacy and political campaign activity can be difficult to discern." Factors that indicate genuine issue advocacy include whether a communication is part of an ongoing effort, does not refer to an election or does not identify candidates or comment on their positions. The report goes into more detail in a later section on 527 political committees, noting factors that tend to separate genuine issue advocacy from electioneering. These include communications that identify a candidate is identified "solely as a government official who is in a position to act on an issue," targeted to specific legislation, timed to coincide with an event outside the organization's control or is part of a series of similar advocacy on the same issue.
• Selling mailing lists and other business activities is permissible if not biased towards any candidate or party, customary and usual rates are charged and the lists or facilities "are available to all candidates on an equal basis."
• Website links to partisan content on another site may be considered a partisan communication of the linking site, depending on the context, whether all candidate sites are linked and whether the link serves an exempt purpose, such as voter education.
• Activities by the organization's leaders and members in their private capacity, and not supported by the organization, are permissible. "Individuals may be identified as being associated with an organization, but there should be no indication that their views represent the organization."

501(c)(4),(5) and (6) Organizations The report notes that 501(c)(4) social welfare organizations, 501(c)(5) labor unions and 501(c)(6) trade associations have no limitation on the amount of lobbying they do. They may engage in partisan electoral activity "so long as it is consistent with the organization's tax-exempt purpose." However, electioneering cannot be their primary activity. The report explains that many of these organizations can create separate segregated funds to pay for partisan campaigning in order to avoid taxes. 527 Political Committees The report clarifies the definition and regulation of 527 groups, stating, "IRC Section 527 encompasses every kind of political committee, including a candidate committee, a political party, and a political action committee set up by a union, a corporation or a group of politically interested citizens." It notes that in 2000 Congress began requiring 527s that work on federal elections but do not report to the Federal Election Commission to register with the IRS and file reports on contributions and expenditures.