26 C.F.R. § 53.4941(c)-1
Example. A and B, who are managers of private foundation X, lend one of the foundation's paintings to G, a disqualified person, for display in G's office, in a transaction which gives rise to liability for tax under section 4941(a)(2) (relating to tax on foundation managers). An initial tax is imposed on both A and B with respect to the act of lending the foundation's painting to G. A and B are jointly and severally liable for the tax.
Example. A, a disqualified person with respect to private foundation Y, sells certain real estate having a fair market value of $500,000 to Y for $500,000 in cash. B, C, and D, all the managers of foundation Y, authorized the purchase on Y's behalf knowing that such purchase was an act of self-dealing. The actions of B, C, and D in approving the purchase were willful and not due to reasonable cause. Initial taxes are imposed upon the foundation managers under subsections (a)(2) and (c)(2) of section 4941. The tax to be paid by the foundation managers is $10,000 (the lesser of $10,000 or 21/2 percent of the amount involved). The managers are jointly and severally liable for this $10,000, and this sum may be collected by the Internal Revenue Service from any one of them.
26 C.F.R. §53.4941(c)-1