(a) In general. For purposes of this section, the term “two or more trades or businesses under common control” means any group of trades or businesses which is either a “parent-subsidiary group of trades or businesses under common control” as defined in paragraph (b) of this section, a “brother-sister group of trades or businesses under common control” as defined in paragraph (c) of this section, or a “combined group of trades or businesses under common control” as defined in paragraph (d) of this section. For purposes of this section and §§ 1.414(c)-3 and 1.414(c)-4, the term “organization” means a sole proprietorship, a partnership (as defined in section 7701(a)(2)), a trust, an estate, or a corporation.

(b) Parent-subsidiary group of trades or businesses under common control—(1) In general. The term “parent-subsidiary group of trades or businesses under common control” means one or more chains of organizations conducting trades or businesses connected through ownership of a controlling interest with a common parent organization if—

(i) A controlling interest in each of the organizations, except the common parent organization, is owned (directly and with the application of § 1.414(c)-4(b)(1), relating to options) by one or more of the other organizations; and

(ii) The common parent organization owns (directly and with the application of § 1.414(c)-4(b)(1), relating to options) a controlling interest in at least one of the other organizations, excluding, in computing such controlling interest, any direct ownership interest by such other organizations.

(2) Controlling interest defined—(i) Controlling interest. For purposes of paragraphs (b) and (c) of this section, the phrase “controlling interest” means:

(A) In the case of an organization which is a corporation, ownership of stock possessing at least 80 percent of total combined voting power of all classes of stock entitled to vote of such corporation or at least 80 percent of the total value of shares of all classes of stock of such corporation;

(B) In the case of an organization which is a trust or estate, ownership of an actuarial interest of at least 80 percent of such trust or estate;

(C) In the case of an organization which is a partnership, ownership of at least 80 percent of the profits interest or capital interest of such partnership; and

(D) In the case of an organization which is a sole proprietorship, ownership of such sole proprietorship.

(ii) Actuarial interest. For purposes of this section, the actuarial interest of each beneficiary of trust or estate shall be determined by assuming the maximum exercise of discretion by the fiduciary in favor of such beneficiary. The factors and methods prescribed in § 20.2031-7 or, for certain prior periods, § 20.2031-7A (Estate Tax Regulations) for use in ascertaining the value of an interest in property for estate tax purposes shall be used for purposes of this subdivision in determining a beneficiary's actuarial interest.

(c) Brother-sister group of trades or businesses under common control—(1) In general. The term “brother-sister group of trades or businesses under common control” means two or more organizations conducting trades or businesses if (i) the same five or fewer persons who are individuals, estates, or trusts own (directly and with the application of § 1.414(c)-4) a controlling interest in each organization, and (ii) taking into account the ownership of each such person only to the extent such ownership is identical with respect to each such organization, such persons are in effective control of each organization. The five or fewer persons whose ownership is considered for purposes of the controlling interest requirement for each organization must be the same persons whose ownership is considered for purposes of the effective control requirement.

(2) Effective control defined. For purposes of this paragraph, persons are in “effective control” of an organization if—

(i) In the case of an organization which is a corporation, such persons own stock possessing more than 50 percent of the total combined voting power of all classes of stock entitled to vote or more than 50 percent of the total value of shares of all classes of stock of such corporation;

(ii) In the case of an organization which is a trust or estate, such persons own an aggregate actuarial interest of more than 50 percent of such trust or estate;

(iii) In the case of an organization which is a partnership, such persons own an aggregate of more than 50 percent of the profits interest or capital interest of such partnership; and

(iv) In the case of an organization which is a sole proprietorship, one of such persons owns such sole proprietorship.

(d) Combined group of trades or businesses under common control. The term “combined group of trades or businesses under common control” means any group of three or more organizations, if (1) each such organization is a member of either a parent-subsidiary group of trades or businesses under common control or a brother-sister group of trades or businesses under common control, and (2) at least one such organization is the common parent organization of a parent-subsidiary group of trades or businesses under common control and is also a member of a brother-sister group of trades or businesses under common control.

(e) Examples. The definitions of parent-subsidiary group of trades or businesses under common control, brother-sister group of trades or businesses under common control, and combined group of trades or businesses under common control may be illustrated by the following examples.

Example 1.(a) The ABC partnership owns stock possessing 80 percent of the total combined voting power of all classes of stock entitled to voting of S corporation. ABC partnership is the common parent of a parent-subsidiary group of trades or businesses under common control consisting of the ABC partnership and S Corporation.

(b) Assume the same facts as in (a) and assume further that S owns 80 percent of the profits interest in the DEF Partnership. The ABC Partnership is the common parent of a parent-subsidiary group of trades or businesses under common control consisting of the ABC Partnership, S Corporation, and the DEF Partnership. The result would be the same if the ABC Partnership, rather than S, owned 80 percent of the profits interest in the DEF Partnership.

Example 2.L Corporation owns 80 percent of the only class of stock of T Corporation, and T, in turn, owns 40 percent of the capital interest in the GHI Partnership. L also owns 80 percent of the only class of stock of N Corporation and N, in turn, owns 40 percent of the capital interest in the GHI Partnership. L is the common parent of a parent-subsidiary group of trades or businesses under common control consisting of L Corporation, T Corporation, N Corporation, and the GHI Partnership. Example 3.ABC Partnership owns 75 percent of the only class of stock of X and Y Corporations; X owns all the remaining stock of Y, and Y owns all the remaining stock of X. Since interorganization ownership is excluded (that is, treated as not outstanding) for purposes of determining whether ABC owns a controlling interest of at least one of the other organizations, ABC is treated as the owner of stock possessing 100 percent of the voting power and value of all classes of stock of X and of Y for purposes of paragraph (b)(1)(ii) of this section. Therefore, ABC is the common parent of a parent-subsidiary group of trades or businesses under common control consisting of the ABC Partnership, X Corporation, and Y Corporation. Example 4.Unrelated individuals A, B, C, D, E, and F own an interest in sole proprietorship A, a capital interest in the GHI Partnership, and stock of corporations M, W, X, Y, and Z (each of which has only one class of stock outstanding) in the following proportions:

Organizations

Individuals	A	GHI	M	W	X	Y	Z	A	100%	50%	100%	60%	40%	20%	60%	B	—	40%	—	15%	40%	50%	30%	C	—	—	—	—	10%	10%	10%	D	—	—	—	25%	—	20%	—	E	—	10%	—	—	10%	—	—		100%	100%	100%	100%	100%	100%	100%

Under these facts the following four brother-sister groups of trades or businesses under common control exist: GHI, X and Z; X, Y and Z; W and Y; A and M. In the case of GHI, X, and Z, for example, A and B together have effective control of each organization because their combined identical ownership of GHI, X and Z is greater than 50%. (A's identical ownership of GHI, X and Z is 40% because A owns at least a 40% interest in each organization. B's identical ownership of GHI, X and Z is 30% because B owns at least a 30% interest in each organization.) A and B (the persons whose ownership is considered for purposes of the effective control requirement) together own a controlling interest in each organization because they own at least 80% of the capital interest of partnership GHI and at least 80% of the total combined voting power of corporations X and Z. Therefore, GHI, X and Z comprise a brother-sister group of trades or businesses under common control. Y is not a member of this group because neither the effective control requirement nor the 80% controlling interest requirement are met. (The effective control requirement is not met because A's and B's combined identical ownership in GHI, X, Y and Z (20% for A and 30% for B) does not exceed 50%. The 80% controlling interest test is not met because A and B together only own 70% of the total combined voting power of the stock of Y.) A and M are not members of this group because B owns no interest in either organization and A's ownership of GHI, X and Z, considered alone, is less than 80%. Example 5.The outstanding stock of corporations U and V, which have only one class of stock outstanding, is owned by the following unrelated individuals:

Corporations

Individuals	U	V	(percent)	(percent)	A	12	12	B	12	12	C	12	12	D	12	12	E	13	13	F	13	13	G	13	13	H	13	13		100	100

Any group of five of the shareholders will own more than 50 percent of the stock in each corporation, in identical holdings. However, U and V are not members of a brother-sister group of trades or businesses under common control because at least 80 percent of the stock of each corporation is not owned by the same five or fewer persons. Example 6.A, an individual, owns a controlling interest in ABC Partnership and DEF Partnership. ABC, in turn, owns a controlling interest in X Corporation. Since ABC, DEF, and X are each members of either a parent-subsidiary group or a brother-sister group of trades or businesses under common control, and ABC is the common parent of a parent-subsidiary group of trades or businesses under common control consisting of ABC and X, and also a member of a brother-sister group of trades or businesses under common control consisting of ABC and DEF, ABC Partnership, DEF Partnership, and X Corporation are members of the same combined group of trades or businesses under common control. [T.D. 8179, 53 FR 6606, Mar. 2, 1988, as amended by T.D. 8540, 59 FR 30102, June 10, 1994]