Treas. Reg. § 1.501(c)(21)-1

(a) Created or organized in the United States. A trust is not created or organized in the United States unless it is maintained at all times as a domestic trust in the United States. For this purpose, section 7701(a)(9) limits the term United States to the District of Columbia and States of the United States.

(b) Insurance company. The term insurance company means an insurance, surety, bonding or other company whose liability for the kinds of claims to which section 501(c)(21)(A)(i) applies is as an insurer or guarantor of the liabilities of another.

(c) Black Lung Acts. The term Black Lung Acts includes any State law providing compensation for disability or death due to pneumoconiosis even though the State law compensates for other kinds of injuries. In such a case, section 501(c)(21) applies only to the extent that the liability is attributable to disability or death due to pneumoconiosis. For this purpose, the term pneumoconiosis has the same meaning as it has under federal law. See 30 U.S.C. 902.

(d) Insurance exclusively covering such liability. The term insurance exclusively covering such liability includes insurance that covers risk for liabilities in addition to the liabilities to which section 501(c)(21)(A)(i) applies. In such a case, payment for premiums may be made from the trust only to the extent of that portion of the premiums that has been separately allocated and stated by the insurer as attributable solely to coverage of the liabilities to which section 501(c)(21)(A)(i) applies.

(e) Administrative and other incidental expenses. The term administrative and other incidental expenses means expenditures that are appropriate and helpful to the trust making them in carrying out the purposes for which its assets may be used under section 501(c)(21)(B). The term includes any exicse tax imposed on the trust under section 4952 (relating to taxes on taxable expenditures) and reasonable expenses, such as legal expenses, incurred by the trust in connection with an assertion against the trust of liability for a taxable expenditure. The term does not include an excise tax imposed on the trustee or on other disqualified persons under section 4951 (relating to taxes on self-dealing) or under section 4953 (relating to tax on excess contributions to black lung benefit trusts) or any expenses incurred in connection with the assertion of these taxes other than expenses that are treated as part of reasonable compensation under section 4951(d)(2)(C). See §§ 53.4941 (d)-2(f)(3) and (d)-3(c) for interpretations of similar provisions under section 4941(d)(2)(E), relating to reasonable compensation for private foundation disqualified persons.

(f) Public debt securities of the United States. The term public debt securities of the United States means obligations that are taken into consideration for purposes of the public debt limit. See, for example 31 U.S.C. 757b.

(g) Obligations of a State or local government. The term obligations of a State or local government means the obligations of a State or local governmental unit the interest on which is exempt from tax under section 103(a). See § 1.103-1(a).

(h) Time or demand deposits. The term time or demand deposits includes checking accounts, savings accounts, certificates of deposit or other time or demand deposits. The term does not include common or collective trust funds such as a common trust fund as defined in section 584.