Generally, under section 4943 of the Internal Revenue Code, the combined holdings of a private foundation and all of its disqualified persons are limited to 20 percent of the voting stock in a business enterprise that is a corporation. The 20 percent limitation also applies to holdings in business enterprises that are partnerships, joint ventures, or other unincorporated enterprises. For a partnership or joint venture, profits interest is substituted for voting stock, and for any other unincorporated enterprise, beneficial interest is substituted for voting stock. A private foundation that has excess business holdings in a business enterprise may become liable for an excise tax based on the amount of the excess holdings.
Initial tax. An excise tax of ten percent of the value of the excess holdings is imposed on the foundation. The tax is imposed on the last day of each tax year that ends during the taxable period
The amount of the excess holdings is determined as of the day during the tax year when the foundation's excess holdings in the business were the greatest.
The initial tax may be abated if the foundation can show that the excess holdings were due to reasonable cause and not to willful neglect, and that the excess holdings were disposed of within the correction period.
For purposes of the taxes under section 4943, certain donor-advised funds and supporting organizations are treated as private foundations.
Additional tax. After the initial tax has been imposed, an excise tax of 200 percent of the excess holdings is imposed on the foundation if it has not disposed of the remaining excess business holdings by the end of the taxable period. The additional tax will not be assessed, or if assessed will be abated, if the excess business holdings are reduced to zero during the correction period.