In February 2010, the same month the tea-party targeting started, according to a recent inspector general’s report, Freedom’s Watch was subjected to an IRS audit that focused largely on its political activities, an uncommon but not unprecedented action, election lawyers say. The probe broadened into other areas, including executive compensation.

About a year later, as many as five donors to Freedom’s Watch were subjected to IRS audits of their contributions that sought to impose gift taxes on their donations to the group, according to lawyers and former officials of Freedom’s Watch.

Tax experts say that effort was highly unusual. The IRS generally hadn’t sought to impose the gift tax on donations to tax-exempt groups such as Freedom’s Watch in at least 20 years, perhaps longer, following an unfavorable court ruling and changes in the law by Congress, according to lawyers and IRS documents.