A 501(c) organization is a nonprofit organization in the federal law of the United States according to 26 U.S.C. and is one of 29 types of nonprofit organizations which are exempt from some federal income taxes. Sections 503 through 505 set out the requirements for attaining such exemptions. Many states refer to Section 501(c) for definitions of organizations exempt from state taxation as well. 501(c) organizations can receive unlimited contributions from individuals, corporations, and unions.
For example, a nonprofit organization may be tax-exempt under section 501(c)(3) if its primary activities are charitable, religious, educational, scientific, literary, testing for public safety, fostering amateur sports competition, preventing cruelty to children, or preventing cruelty to animals.
According to the IRS Publication 557, in the Organization Reference Chart section, the following is an exact list of 501(c) organization types and their corresponding descriptions.
- 501(c)(1) – Corporations Organized Under Act of Congress (including Federal Credit Unions)
- 501(c)(2) – Title-holding Corporation for Exempt Organization
- 501(c)(3) – Religious, Educational, Charitable, Scientific, Literary, Testing for Public Safety, to Foster National or International Amateur Sports Competition, or Prevention of Cruelty to Children or Animals Organizations
- – Civic Leagues, Social Welfare Organizations, and Local Associations of Employees
- – Labor, Agricultural and Horticultural Organizations
- – Business Leagues, Chambers of Commerce, Real Estate Boards, etc.
- – Social and Recreational Clubs
- – Fraternal Beneficiary Societies and Associations
- 501(c)(9) – Voluntary Employee Beneficiary Associations
- 501(c)(10) – Domestic Fraternal Societies and Associations
- 501(c)(11) – Teachers' Retirement Fund Associations
- 501(c)(12) – Benevolent Life Insurance Associations, Mutual Ditch or Irrigation Companies, Mutual or Cooperative Telephone Companies, etc.
- 501(c)(13) – Cemetery Companies
- 501(c)(14) – State-Chartered Credit Unions, Mutual Reserve Funds
- 501(c)(15) – Mutual Insurance Companies or Associations
- 501(c)(16) – Cooperative Organizations to Finance Crop Operations
- 501(c)(17) – Supplemental Unemployment Benefit Trusts
- 501(c)(18) – Employee Funded Pension Trust (created before June 25, 1959)
- 501(c)(19) – Post or Organization of Past or Present Members of the Armed Forces
- 501(c)(20) – Group Legal Services Plan Organizations
- 501(c)(21) – Black Lung Benefit Trusts
- 501(c)(22) – Withdrawal Liability Payment Fund
- 501(c)(23) – Veterans Organization
- 501(c)(24) – Section 4049 ERISA Trusts
- 501(c)(25) – Title Holding Corporations or Trusts with Multiple Parents
- 501(c)(26) – State-Sponsored Organization Providing Health Coverage for High-Risk Individuals
- 501(c)(27) – State-Sponsored Workers' Compensation Reinsurance Organization
- 501(c)(28) – National Railroad Retirement Investment Trust
- 501(c)(29) – Qualified Nonprofit Health Insurance Issuers
Other tax-exempt organizations
- 501(d) – Apostolic organizations with the purpose of operating a religious community where the members live a communal life following the tenets and teachings of the organization. The organization's property is owned by each of the individuals in the community but, upon leaving, a member cannot withdraw any of the community's assets. The organization's income goes into a community treasury that is used to pay for the organization's operating expenses and supporting members and their families.
- 501(e) – Cooperative hospital service organizations that are organized to provide services for multiple tax-exempt hospitals. 
- 501(f) – Cooperative service organizations of educational organizations that invest assets contributed by each of the organization's members. 
- 501(j) – Amateur sports organizations that either conduct national or international sporting competitions or develop amateur athletes for national or international sporting competitions.
- 501(k) – Day care centers may qualify as tax-exempt under Section 501(k). The day care center must provide child care away from their homes. At least 85 percent of the children served must be cared for while their parent or guardian is either employed, seeking employment, or a full-time student. Most of the day care center's funding must come from fees received for day care services. The day care center must also provide child care services to the general public. The tax exemption for certain day care centers was part of the Deficit Reduction Act of 1984.
- 501(n) – Charitable risk pools that pool insurable risks of its members, which are tax-exempt charities. 
- 521(a) – Farmers' cooperative associations that market its member farmers' products at market rates, make purchases at wholesale rates, and remit earnings to member farmers. 
- 527 – Political organizations that operate primarily to raise or spend money to influence the selection, nomination, election, or appointment of any individual to any Federal, State, or local public office,  such as political parties, political action committees, and Super PACs.
- 528 – Homeowner associations, condominium management associations, residential real estate management associations, and timeshare associations may elect to be exempt from income tax on their exempt-function income under Section 528.     Alternatively, some homeowner associations may qualify under Section 501(c)(4) instead.   A homeowner association that provides only social and recreational activities may qualify under Section 501(c)(7). 
- 529 – Qualified tuition plans operated by a state or educational institution. 
- 4947(a)(1) – Non-exempt charitable trusts that have exclusively charitable interests.
- 4947(a)(2) – Split-interest trusts.
- 170(c)(1) – Government entities. 
Under Section 511, a 501(c) organization is subject to tax on its " unrelated business income ", whether or not the organization actually makes a profit, but not including selling donated merchandise or other business or trade carried on by volunteers, or certain bingo games.  Disposal of donated goods valued over $2,500, or acceptance of goods worth over $5,000 may also trigger special filing and record-keeping requirements.
Tax exemption does not excuse an organization from maintaining proper records and filing any required annual or special-purpose tax returns, e.g., 26 U.S.C. and 26 U.S.C.. Prior to 2008, an annual return was not generally required from an exempt organization accruing less than $25,000 in gross income yearly.  Since 2008, most organizations whose annual gross receipts are less than $50,000 must file an annual information return known as Form 990-N. Form 990-N must be submitted electronically using an authorized IRS e-file provider. Form 990, Form 990-EZ, and Form 990-PF may be filed either by mail or electronically through an authorized e-file provider.
Failure to file required returns such as Form 990 (Return of Organization Exempt From Income Tax) may result in fines of up to $250,000 per year. Exempt or political organizations, excluding churches or similar religious entities, must make their returns, reports, notices, and exempt applications available for public inspection. The organization's Form 990 (or similar such public record as the Form 990-EZ or Form 990-PF) is available for public inspection and photocopying at the offices of the exempt organization, through a written request and payment for photocopies by mail from the exempt organization, or through a direct Form 4506-A "Request for Public Inspection or Copy or Political Organization IRS Form" request to the IRS of for the past three tax years. Form 4506-A also allows the public inspection or photocopying access to Form 1023 "Application for Recognition of Exemption" or Form 1024, Form 8871 "Political Organization Notice of Section 527 Status", and Form 8872 "Political Organization Report of Contribution and Expenditures". Internet access to many organizations' 990 and some other forms are available through GuideStar. Certain organizations are exempt from filing Form 990, such as churches, their integrated auxiliaries, and conventions or associations of churches; the exclusively religious activities of any religious order; and religious organizations; and most organizations whose annual gross receipts are less than $5,000. Failure to file such timely returns and to make other specific information available to the public also is prohibited. 
501(c)(3) tax-exemptions apply to entities that are organized and operated exclusively for religious, charitable, scientific, literary, or educational purposes, or for testing for public safety, or to foster national or international amateur sports competition, or for the prevention of cruelty to children or animals. The 501(c)(3) exemption also applies for any unincorporated community chest, fund, cooperating association, or foundation that is organized and operated exclusively for those purposes. There are also supporting organizations—often referred to in shorthand form as "Friends of" organizations. 26 U.S.C., provides a deduction, for federal income tax purposes, for some donors who make charitable contributions to most types of 501(c)(3) organizations, among others.
Organizations described in section 501(c)(3) are prohibited from conducting political campaign activities to intervene in elections to public office. On the other hand, public charities (but not private foundations) may conduct a limited amount of lobbying to influence legislation. Although the law states that "No substantial part..." of a public charity's activities can go to lobbying, charities may register for a 501(h) election allowing them to lawfully conduct lobbying activities as long as their financial expenditure does not exceed a specified amount. 501(c)(3) organizations risk loss of tax exempt status if any of these rules are violated.
A 501(c)(3) organization is allowed to conduct some or all of its charitable activities outside the United States.   Donors' contributions to a 501(c)(3) organization are tax-deductible only if the contribution is for the use of the 501(c)(3) organization, and that the 501(c)(3) organization is not merely serving as an agent or conduit of a foreign charitable organization.  Additional procedures are required of 501(c)(3) organizations that are private foundations. 
A 501(c)(4) organization is a social welfare organization, such as a civic organization or a neighborhood association. An organization is considered by the IRS to be operated exclusively for the promotion of social welfare if it is primarily engaged in promoting the common good and general welfare of the people of the community.  Net earnings must be exclusively used for charitable, educational, or recreational purposes.
According to The Washington Post :
These groups are allowed to participate in politics, so long as politics do not become their primary focus. What that means in practice is that they must spend less than 50 percent of their money on politics. So long as they don't run afoul of that threshold, the groups can influence elections, which they typically do through advertising.
501(c)(4) are similar to 501(c)(5) and 501(c)(6) in that the organizations may inform the public on controversial subjects and attempt to influence legislation relevant to its program  and, unlike 501(c)(3) organizations, they may also participate in political campaigns and elections, as long as their primary activity is the promotion of social welfare and related to the organization's purpose. 
The income tax exemption for 501(c)(4) organizations applies to most of their operations, but income spent on political activities—generally the advocacy of a particular candidate in an election—is taxable. An "action" organization generally qualifies as a 501(c)(4) organization. An "action" organization is one whose activities substantially include, or are exclusively, direct or grassroots lobbying related to advocacy for or against legislation or proposing, supporting, or opposing legislation that is related to its purpose. 
A 501(c)(4) organization may directly or indirectly support or oppose a candidate for public office as long as such activities are not a substantial amount of its activities. 
A 501(c)(4) organization that lobbies must register with the Clerk of the House if it lobbies members of the House or their staff.  Likewise, a 501(c)(4) organization must register with the Secretary of the Senate if it lobbies members of the Senate or their staff.  In addition, the 501(c)(4) organization must either inform its members the amount it spends on lobbying or pay a proxy tax to the Internal Revenue Service.  Lobbying expenses and political expenses are not deductible as business expenses. 
The use of 501(c)(4), 501(c)(5), and 501(c)(6) organizations has been affected by the 2007 FEC v. Wisconsin Right to Life, Inc., in which the Supreme Court struck the part of the McCain-Feingold Act that prohibited 501(c)(4), 501(c)(5), and 501(c)(6) from broadcasting electioneering communications. The Act defined an electioneering communication as a communication that mentions a candidate's name 60 days before a primary or 30 days before a general election.
Contributions to 501(c)(4) organizations are not tax-deductible as charitable donations unless the organization is either a volunteer fire department or a veterans organization. Dues or contributions to 501(c)(4) organizations may be deductible as a business expense under IRC 162, although amounts paid for intervention or participation in any political campaign, direct lobbying, grass roots lobbying, and contact with certain federal officials are not deductible. If a 501(c)(4) engages in a substantial amount of these activities, then only the amount of dues or contributions that can be attributed to other activities may be deductible as a business expense.
The organization must provide a notice to its members containing a reasonable estimate of the amount related to lobbying and political campaign expenditures, or else it is subject to a proxy tax on its lobbying and political campaign expenditures. It must also state that contributions to the organization are not deductible as charitable contributions during fundraising.
501(c)(4) organizations are not required to disclose their donors publicly.  The lack of disclosure has led to extensive use of the 501(c)(4) provisions for organizations that are actively involved in lobbying, and has become controversial.  Criticized as " dark money ", spending from these organizations on political TV ads has exceeded spending from Super PACs.  Spending by organizations that do not disclose their donors has increased from less than $5.2 million in 2006 to well over $300 million in the 2012 election. 
The origins of 501(c)(4) organizations date back to the Revenue Act of 1913, which created a new group of tax-exempt organizations dedicated to social welfare in a precursor to what is now Internal Revenue Code Section 501(c)(4).
The Protecting Americans from Tax Hikes Act of 2015 introduced a new requirement on 501(c)(4) organizations.  Within 60 days of the organization's formation, a 501(c)(4) organization is required to file Form 8976 with the Internal Revenue Service as notification that it is operating as a section 501(c)(4) organization.   The Internal Revenue Service will acknowledge receipt of the notification, but the acknowledgment is not a determination that the organization qualifies for section 501(c)(4) tax-exempt status.  A 501(c)(4) organization is not required to send the notification if the organization was formed on or before July 8, 2016, and it either applied for a determination letter using Form 1024 or filed a Form 990 between December 19, 2015 and July 8, 2016. 
A 501(c)(5) organization is a labor organization, an agricultural organization, or a horticultural organization. Labor unions, county fairs, and flower societies are examples of these types of groups. Labor union organizations were a primary benefactor of this organization type, dating to the 19th century. According to the Internal Revenue Service, a 501(c)(5) organization has a duty of providing service to its members first. The organization's benefits may not inure to a specific member, but the rules for inurement vary among the three different types of organizations under this segment. A 501(c)(5) organization can make unlimited corporate, individual, or union contributions. 
A labor organization may pay benefits to its members because paying benefits improves all members' shared working conditions. An agricultural organization can provide financial assistance to its members in order to improve the conditions of those engaged in agricultural pursuits generally. Members can benefit in incidental ways from the organization's exempt activities as long as the benefits are available to all persons. 
The Revenue Act of 1913 excluded "labor, agricultural, or horticultural organizations" from income tax liability.
Contributions and activities
Much like 501(c)(4) and 501(c)(6) organizations, 501(c)(5) organizations may also perform some political activities.  501(c)(5) organizations are allowed to attempt to influence legislation that is related to the common union interests of its members. 
501(c)(5) organizations can receive unlimited contributions from corporations, individuals, and labor unions. The names and addresses of contributors are not required to be made available for public inspection.  All other information, including the amount of contributions, the description of noncash contributions, and any other information, is required to be made available for public inspection unless it clearly identifies the contributor.
A union membership dues paid to a 501(c)(5) organization are generally an ordinary and necessary business expense.  The membership dues are tax-deductible in full unless a substantial part of the 501(c)(5) organization's activities consists of political activity, in which case a tax deduction is allowed only for the portion of membership dues that are for other activities. 
Because associations involved in fishing and seafood harvesting were having difficulties qualifying for reduced postal rates, in 1976 Congress established Internal Revenue Code Section 501(5) to define "agriculture" as the art or science of cultivating land, harvesting crops or aquatic resources, or raising livestock.
A 501(c)(6) organization is a business league, chambers of commerce like the U.S. Chamber of Commerce, a real estate board, a board of trade, a professional football league or an organization like the Edison Electric Institute and the Security Industry Association, that are not organized for profit and no part of the net earnings goes to the benefit of any private shareholder or individual.
Qualifications for exemption
A business league may qualify if it is an association of persons having a common business interest, whose purpose is to promote the common business interest and whose activities improve business conditions rather than actually conduct the business itself.  Members of the organization must be of the same trade, business, occupation, or profession in order to qualify.  A chamber of commerce or board of trade could qualify for similar reasons except that they may promote the common economic interests of all the commercial enterprises in a given trade or community. 
An association would not qualify if its principal activities consist of securing benefits and performing particular services for members.
An association that promotes the common interests of certain hobbyists would not qualify because the Internal Revenue Service does not consider hobbies to be activities conducted as businesses.
An organization whose primary activity is advertising the products or services of its members does not qualify because the organization is performing a service for its members rather than promoting common interests.  If an organization's primary activity is advertising the products or services of its members' industry as a whole, however, the organization will generally qualify if it also performs other services for its members.
Contributions and activities
Much like 501(c)(4) and 501(c)(5) organizations, 501(c)(6) organizations may also perform some political activities.  501(c)(6) organizations are allowed to attempt to influence legislation that is related to the common business interests of its members. 
501(c)(6) organizations can receive unlimited contributions from corporations, individuals, and labor unions. The names and addresses of contributors are not required to be made available for public inspection.  All other information, including the amount of contributions, the description of noncash contributions, and any other information, is required to be made available for public inspection unless it clearly identifies the contributor. The U.S. Chamber of Commerce is a large political spender, and Freedom Partners used its status as a 501(c)(6) organization to raise and distribute over $250 million during the 2012 election campaigns without disclosing its donors.  The group's existence was not publicly known until nearly a year after the election.
A business' membership dues paid to a 501(c)(6) organization are generally an ordinary and necessary business expense.  The membership dues are tax-deductible in full unless a substantial part of the 501(c)(6) organization's activities consists of political activity, in which case a tax deduction is allowed only for the portion of membership dues that are for other activities. 
The predecessor of IRC 501(c)(6) was enacted as part of the Revenue Act of 1913 likely due to a U.S. Chamber of Commerce request for an exemption for nonprofit "civic" and "commercial" organizations, which resulted in IRC 501(c)(4) for nonprofit "civic" organizations and IRC 501(c)(6) for nonprofit "commercially-oriented" organizations. The Revenue Act of 1928 amended the statute to include real estate boards.  In 1966, professional football leagues were added to the described organizations. 
The Revenue Act of 1913 related to professional football leagues had both antitrust and tax provisions: The antitrust provision was enacted to permit the merger of the National and American Football Leagues to go forward without fear of an antitrust challenge under either the 1914 Clayton Antitrust Act or the 1914 Federal Trade Commission Act.  IRC 501(c)(6) amendment was enacted in 1966 to ensure that a professional football league's exemption would not be jeopardized because it administered a players' pension fund.  Additionally, a professional sports league's exemption is not to be jeopardized because its primary source of revenue is the sale of television broadcasting rights to its games because the broadcasting of games increases public awareness of the sport.  
In 2013, Senator Tom Coburn introduced legislation to disallow a tax exemption for the National Football League, the Professional Golfers' Association, and other professional sports organizations.   Coburn estimated the tax exemption cost $100 million, but he said he could not get other members of Congress to support the legislation.  
A 501(c)(7) organization is a social or recreational club that is organized for pleasure, recreation, and other nonprofitable purposes. Members must share interests and have a common goal directed toward pleasure and recreation, and the organization must provide opportunities for personal contact among members.   The organization's facilities and services must be open to its members and their guests only.  The organization must be a club of individuals, and no individual may derive profit from the organization's net earnings.  Examples include college alumni associations ; college fraternities or college sororities operating chapter houses for students; country clubs ; amateur sport clubs ; supper clubs that provide a meeting place, library, and dining room for members; hobby clubs ; and garden clubs. 
A substantial amount of the 501(c)(7) organization's activities must be related to social and recreational activities for its members. No more than 35 percent of its gross receipts may derive from non-members, and no more than 15 percent of its gross receipts is permitted to come from use of its facilities or services by the general public. An organization that exceeds these limits may lose its 501(c)(7) status.
When a group of eight or fewer individuals, at least one of whom is a member, uses the organization's facilities and the member pays for the other individuals, the Internal Revenue Service will assume the nonmembers are the guests of the member, and the revenue is deemed to be derived from the member.  Similarly, if at least 75 percent a group using club facilities are members of the organization, the Internal Revenue Service will assume the nonmembers are the guests of the member, and the revenue is deemed to be derived from the member.  It is the responsibility of the organization to maintain these records. If the organization does not keep sufficient records to link revenue to a member, the Internal Revenue Service assumes the revenue came from a nonmember. 
The organization is subject to unrelated business income tax for the revenue derived from nonmember use of its facilities and services, less allowable deductions. If the organization sells assets that were previously used for recreational or social purposes, the proceeds are not considered unrelated business income as long as the proceeds are reinvested in the organization. 
A 501(c)(7) organization cannot have a policy of discriminating on the basis of race, color, or religion.  Nevertheless, a 501(c)(7) organization is permitted to limit its members to a particular religion in order to further the teachings of that religion.  An auxiliary of a 501(c)(8) fraternal benefit society that limits membership to members of a particular religion is allowed to do so as well.  The Internal Revenue Service has determined that 501(c)(7) are not prohibited from discriminating against ethnic groups. 
An individual's donation to a fraternity is a tax-deductible charitable contribution if the contribution "is to be used exclusively for religious, charitable, scientific, literary, or educational purposes, or for the prevention of cruelty to children or animals." 
The predecessor of Internal Revenue Code Section 501(c)(7) was part of the Revenue Act of 1913, which provides a tax-exemption to "fraternal beneficiary societies, orders, or associations operating under the lodge system or for the exclusive benefit of the members of a fraternity itself operating under the lodge system". Congress justified the tax-exemption with the reasoning that the members join together to provide themselves with recreational or social organization without further tax consequences, similar as if they had paid for the benefits directly. Tax-exemption was available for organizations operated exclusively for pleasure, recreation, and other nonprofitable purposes.
In 1969, Congress passed a law stating that social and recreational clubs were permitted to engage in some unrelated business income, subject to income tax.
A 501(c)(8) organization is a fraternal benefit society.
The society must have members of a similar calling, recreation, or profession, or members who work together to accomplish a worthy goal. The members have associated themselves in order to help each other and to promote the common cause. The society must have written documentation of its eligibility standards for membership, classes of membership, a process of admission, and rights and privileges of members. 
The members must have a common bond, which may be based on religious beliefs, gender, occupation, ethnicity, or shared values. 
The society must have a supreme governing body and subordinate lodges into which members are elected, initiated, or admitted in accordance with its laws. The supreme governing body should be composed of delegates elected directly by members or intermediate assemblies.
The society must offer benefits to members, which may include life insurance, medical insurance, scholarships, educational programs, travel opportunities, and discount programs.  Revenue generated from providing benefits to non-members must be insubstantial to the society and may be taxable as unrelated business income.
Fraternal benefit societies trace their lineage back through mutual benefit societies, friendly societies and eventually to medieval guilds.  Many fraternal benefit societies were founded to serve the needs of immigrants and other under-served groups who shared common bonds of religion, ethnicity, gender, occupation or shared values.
Section 38 of the Payne–Aldrich Tariff Act of 1909 was the first law to provide a tax-exemption for fraternal beneficiary societies. The tax-exemption was later codified as section 501(c)(8) with the Internal Revenue Code of 1954.
- In accordance with the Internal Security Act of 1950, any 501(c), 501(d), or 521 organization loses its tax-exempt status in any taxable year during which the organization is a Communist-action organization or a Communist-infiltrated organization. 
- 501(c)(20) organizations are no longer tax-exempt under Section 501(c)(20) after June 30, 1992, but they may request to become exempt under Section 501(c)(9) effective July 1, 1992.
- Veterans organizations may be exempt under Section 501(c)(23) only if the organization was created before 1880. Other veterans organizations may be exempt under Section 501(c)(4) instead.
- 501(c)(24) organizations are described as Section 4049 ERISA Trusts; Section 4049 of ERISA has been repealed.
- The Section 501(c)(29) tax exemption for qualified nonprofit health Insurance issuers was created in section 1322(h)(1) of the Affordable Care Act 
- Organizations that are not eligible to file Form 990-N include private foundations, most section 509(a)(3) supporting organizations, and organizations exempt under Section 501(c)(1), 501(c)(20), 501(c)(23), 501(c)(24), 501(d), 527, 529, 4947(a)(2), 4947(a)(1). 
- Guidestar access to recent 990 filings is available for free, but requires one to open a free account.