Nonprofit’s political ad may have violated tax law; Wind farm foe criticized Patrick 

The Alliance to Protect Nantucket Sound, the nonprofit group that has spearheaded opposition to the nation’s first offshore wind farm for nearly a decade, may have breached federal tax law by airing a radio ad critical of Governor Deval Patrick in the final days of the governor’s race, according to a Globe review of the Internal Revenue Service code and agency guidelines.

The ad, which aired on five stations covering Greater Boston, the South Shore, and the Worcester area, criticized Patrick for supporting the Cape Wind energy proposal while noting that “the other candidates for governor’’ opposed the project.

“Tired of paying high electric bills?’’ the ad began. “If Governor Patrick has his way, 172 communities across Massachusetts will soon be paying even more.’’ The ad also referred listeners to an Alliance website that drew a sharp contrast between Patrick and Charles D. Baker, his Republican opponent, while urging readers to “get out and vote on Nov. 2.’’

The federal tax code defines a nonprofit group organized for charitable or educational purposes as one that “does not participate in, or intervene in (including the publishing or distributing of statements), any political campaign on behalf of (or in opposition to) any candidate for political office.’’ Donations to such organizations, known as 501(c)(3)s, are tax deduct ible because they are considered nonpartisan contributions to the betterment of society.

Audra Parker, president of the Alliance, said the organization’s radio ad did not violate the IRS tax code’s prohibition on political activity by nonprofit groups because it did not specifically tell listeners to vote for or against a candidate, and because its aim was to educate voters about Cape Wind and the candidates’ views on the proposal.

“We can say that Governor Patrick supports this irresponsible, exorbitantly expensive project. We just can’t say, ‘Don’t vote for Governor Patrick,’ ’’ Parker said. “We’ve been very careful to live within the letter of the law as a 501(c)(3).’’

But IRS guidelines available on the agency’s website say that “501(c)(3) organizations are absolutely prohibited from directly or indirectly participating in, or intervening in, any political campaign on behalf of (or in opposition to) any candidate for elective public office.’’

The guidelines also say that “even if a statement does not expressly tell an audience to vote for or against a specific candidate, an organization delivering the statement is at risk of violating the political campaign intervention prohibition if there is any message favoring or opposing a candidate.’’

In general, 501(c)(3) organizations differ from so-called 527 organizations, advocacy groups that have been active in national politics, because 527s are formed for the purpose of participating in political campaigns, often by funding “issue ads.’’ In addition, contributions to 527s are not considered tax deductible, and many 527s are required to disclose the names of their donors.

Laura J. Kenney, the New England executive director of nonprofit tax services for the accounting firm Grant Thornton, would not comment specifically on the Alliance ad. But she said her general advice to 501(c)(3) clients is to avoid any issue advocacy that appears to favor or oppose a political candidate, “even if they do not make a specific endorsement.’’

Kenney said that nonprofit groups found to have violated the prohibition on political activity are often required to pay an excise tax and report the payment on their tax returns the following year. But violators may also face the loss of their tax-exempt status, she said.

In a recent TaxAlert sent to its nonprofit clients, Grant Thornton said organizations with the same nonprofit tax status as the Alliance “are strictly prohibited from directly or indirectly participating or intervening in any political campaign.’’ The TaxAlert also warned clients that “undertaking any political activity may jeopardize the tax-exempt status of a section 501(c)(3) organization.’’

Earlier this month, Common Cause of Massachusetts, a group that tracks the influence of money in politics, asked the state’s Office of Campaign and Political Finance to investigate the Alliance for failing to report spending on its radio ad.

A law that took effect in January requires all organizations that pay for ads that mention the name of a candidate within 90 days of an election to report the amount of money spent, along with the names of donors who provide the funds.

Shortly after learning of the Common Cause letter, the Alliance reported spending more than $32,500 on the ad with money given by three individuals, including Christy Mihos, a cochairman of the Alliance and a Cape Cod resident who waged an independent campaign for governor four years ago and, briefly, this year.

The Cape Wind proposal calls for building 130 turbines, each 440 feet high, over 24 square miles in Nantucket Sound. The project is expected to add less than $2 a month to the bills of National Grid customers.