The tax-exempt social welfare organizations described in Section 501(c)(4) of the Internal Revenue Code (IRC) must be "primarily engaged in promoting in some way the common good and general welfare of the people of the community." They are permitted to engage in campaign activity under federal law, but must comply with both the IRC and the Federal Election Campaign Act (FECA). The campaign activities of 501(c)(4) groups continue to receive significant scrutiny. These groups are among the entities operating with less restriction due to the Supreme Court's ruling in Citizens United v. FEC . In that case, the Court invalidated the prohibitions in FECA on corporations using their general treasury funds to make independent expenditures and electioneering communications. An "independent expenditure" is spending for a communication that expressly advocates the election or defeat of a clearly identified candidate, and is not made in cooperation with or at the request or suggestion of such candidate or a political party. An "electioneering communication" is a broadcast, cable, or satellite communication that refers to a clearly identified federal candidate, is made within 30 days of a primary or 60 days of a general election, and for House and Senate races, is targeted to the relevant electorate. These FECA prohibitions had affected 501(c)(4) groups in two ways. First, many are incorporated, and thus were prohibited from using their general treasury funds for independent expenditures and electioneering communications unless they qualified for a limited exception. Additionally, prior to Citizens United , no 501(c)(4) organizations—regardless of corporate status—could serve as conduits for corporate or labor union treasury funds to fund independent expenditures and electioneering communications. While 501(c)(4) organizations are operating with less restriction under FECA after Citizens United , there still remain important restrictions and requirements on these groups to engage in campaign activity under both FECA and the IRC. That is, FECA prohibits corporations from using their treasury funds to make contributions to candidates and parties, requiring them to establish a Political Action Committee (PAC) in order to do so; the IRC sets forth certain requirements related to maintaining tax-exempt status; and FECA requires a group whose major purpose is to elect federal candidates to register as a political committee, which means that it must raise and spend campaign funds subject to FECA's contribution limits, source restrictions, and disclosure requirements. Additionally, 501(c)(4) groups are subject to IRC and FECA reporting requirements. All are discussed below. As a threshold matter, it is important to note that while the Supreme Court's decision in Citizens United invalidated the federal ban on corporate treasury funding of independent expenditures and electioneering communications, it did not appear to affect the ban on corporate contributions to political candidates and parties. FECA defines a contribution to include "anything of value" that is given, made available, or rendered to a candidate or political committee. In contrast, an independent expenditure is defined to include "anything of value" that is spent expressly to advocate the election or defeat of a clearly identified candidate and is not made in concert or cooperation with or at the request or suggestion of a candidate or a political party. In an exception to the prohibition, corporations are permitted to use their treasury funds to establish, administer, and solicit contributions to a separate segregated fund—also known as a PAC—and may use such PAC funds for contributions. As a result, 501(c)(4) organizations that are incorporated are still prohibited from using their treasury funds to make contributions to candidates and parties, and would still be required to establish a PAC in order to do so. In addition, no 501(c)(4) organization—regardless of corporate status—can serve as a conduit for corporate or labor union treasury funds to make such contributions. 501(c)(4) organizations must comply with requirements in the IRC in order to maintain their tax-exempt status. For those groups choosing to engage in campaign activity, two restrictions stand out. First, under a Treasury regulation, campaign activity (along with any other non-exempt purpose activity) cannot be the organization's primary activity. Second, the IRS has ruled that a group which primarily benefits partisan interests could jeopardize its 501(c)(4) status. First, campaign activity (along with any other non-exempt purpose activity) cannot be a 501(c)(4) organization's primary activity. While no statute expressly addresses the ability of 501(c)(4) groups to engage in campaign activity, this limitation is implicit in the statutory requirement in Section 501(c)(4) that organizations be "operated exclusively for the promotion of social welfare." This language raises two questions: (1) what does "exclusively" mean; and (2) is campaign activity part of a "social welfare purpose." A Treasury regulation answers both questions and, as such, is the source of the standard. First, the regulation states that a group is "operated exclusively for the promotion of social welfare if it is primarily engaged in promoting in some way the common good and general welfare of the people of the community." Second, it clarifies that engaging in campaign activity does not count as promoting social welfare. Putting these two concepts together creates the standard: since the primary purpose of these 501(c)(4) organizations must be promoting social welfare, campaign activity (and any other non-exempt purpose activities) cannot be their primary activity. Some might take issue with the regulation interpreting "exclusively" to mean "primarily." If the interpretation were challenged in court, a court would likely begin by examining the plain meaning of the statutory language at issue. When courts are faced with interpreting a statutory term, they generally begin by looking at whether the term is defined in the statute or elsewhere in the U.S. Code, such as the Dictionary Act. If there is no definition, courts then typically look to see if the term has an accepted meaning in law (i.e., is a "term of art"). Words and phrases that are not terms of art or defined by statute are customarily given their ordinary meanings, often derived from the dictionary. Here, the term "exclusively" is not defined in statute, whether in the IRC or somewhere else. This may lead some to think the term should be given its ordinary and customary definition. The dictionary definition of "exclusively" is "only" or "solely," which suggests the IRS interpretation is overly broad. However, this is an example of where a term's statutory meaning might not be obvious on its face. In a 1945 case, the Supreme Court found that a Social Security Act requirement that an organization be operated "exclusively" for certain tax-exempt purposes "plainly means that the presence of a single [non-exempt] purpose, if substantial in nature , will destroy the exemption regardless of the number or importance of truly [exempt] purposes." In other words, an organization may engage in activities for a non-exempt purpose so long as those activities are insubstantial. The Court found the organization did not qualify for the exemption because "an important, if not the primary, pursuit" of the group was engaging in non-exempt purpose activities. This case may provide support for the IRS's interpretation of the law to permit 501(c)(4) groups to engage in some campaign activity even though the statute says they must be operated "exclusively" for social welfare purposes. Additional support might be found in the IRC's income tax scheme on 501(c) groups with unrelated business income, as it may suggest that Congress recognized 501(c) organizations could engage in some activity outside their tax-exempt purpose. Some, while conceding these points, might still argue that the IRS nonetheless was wrong to use "primarily" as the standard because it may permit more campaign activity than would be allowed under a "substantial in nature" test. The basis for this argument is that the regulation's use of the term "primarily" may suggest campaign activity is permissible so long as it (and any other non-exempt purpose activity) is less than 50% of the group's activities, while an "insubstantial" standard would seem to permit a lesser amount of such activity. In order to assess this argument, it seems necessary to have a better understanding of how the IRS interprets the regulation in practice. A potential added wrinkle is that the primary purpose test is found in a regulation. Courts grant varying levels of deference to agency interpretations of statutes, and it is possible a court might provide the regulation with the highest level of deference. Under it, a court first looks at whether Congress has "directly spoken to the precise question at issue." If yes, then that is the end of the matter because the "law must be given effect." But if the statute does not directly address the issue, then "the court does not simply impose its own construction of the statute," but rather determines whether the agency interpretation is a permissible construction of the statute. If so, the court will generally defer to the agency's position, regardless of whether "it is the only possible interpretation or even the one a court might think best." Here, if a court found that Congress did not speak to the issue, as perhaps evidenced by the Supreme Court's 1945 case, then a court might uphold the regulation's interpretation as permissible, even if other interpretations could also be justified. The tax code and regulations do not address how to determine whether a 501(c)(4) organization's campaign activity (and any other non-exempt purposes activity) is its primary activity. Applying the standard that campaign activity (along with any other non-exempt purpose activity) cannot be the organization's primary activity raises three basic questions: what does "primary" mean; what is considered campaign activity; and how are the organization's activities to be measured. There does not appear to be any significant IRS guidance on these issues.