Filing of form—(1) In general. For each tax year that a corporation is a component member of the same controlled group of corporations on a December 31st (its testing date), or, in the case of a short-year member (see section 1561(b) and § 1.1561-2(e)), the date substituted for that December 31st date (its testing date), such corporation and all the other component members of such group each must file the required form (that is, Schedule O or any successor form) with the Federal income tax return for that component member's tax year that includes a particular testing date. Each such corporation must file that form with its return whether or not—

An apportionment plan is in effect; or

Any change is made to the group's apportionment of its section 1561(a) tax benefit items from the previous year.

Exception for component members that are members of a consolidated group. If any of the component members of a controlled group of corporations are also members of a consolidated group, the parent of such consolidated group shall file only one form on behalf of all such members. Such form shall contain the information required for each such member.

No apportionment plan in effect. If the component members of a controlled group of corporations do not have an apportionment plan in effect, the amounts of the section 1561(a) items must be divided equally among all such members. For purposes of the preceding sentence, if any of the component members of a controlled group of corporations are also members of a consolidated group, such members will each be treated as a separate component member of the controlled group.

Apportionment plan in effect—(1) Adoption of plan. The component members of a controlled group of corporations consent to the adoption (or amendment) of an apportionment plan by checking the box to that effect on such form. For purposes of this paragraph (c)—

An apportionment plan that is adopted (including a plan that has been amended) continues in effect until it is terminated;

A consolidated group is treated collectively as one component member of such group. This treatment occurs even where a member of that consolidated group has joined or left the group, if after such corporation joins or leaves the consolidated group, that group remains in existence, pursuant to § 1.1502-75(d); and

The members must allocate the amounts of the section 1561(a) items between/among themselves as described in the plan.

Limitation on adopting a plan—(i) Sufficient statute of limitations period for making an assessment of tax. The members may only adopt or amend such a plan if there is at least one year remaining in the statutory period (including any extensions thereof) for the assessment of a deficiency against every member the tax liability of which would be increased by the adoption of such a plan.

Insufficient statute of limitations period for making an assessment of tax. If any member cannot satisfy the requirement of paragraph (c)(2)(i) of this section, the members may not adopt or amend such a plan unless the member not satisfying such requirement has entered into an agreement with the Internal Revenue Service to extend the statute of limitations for the limited purpose of assessing any deficiency against such member attributable to the adoption of such a plan.

Termination of plan. An apportionment plan that is in effect for the component members of a controlled group with respect to a preceding December 31st is terminated with respect to the current December 31st if—

Each member of such group consents to the termination of such a plan for the current December 31st by checking the box to that effect on its form;

The controlled group ceases to remain in existence (within the meaning of section 1563(a)) during the calendar year ending on the current December 31st;

Any corporation which was a component member of such group on the preceding December 31st is not a component member of such group on the current December 31st; or

Any corporation which was not a component member of such group on the preceding December 31st is a component member of such group on the current December 31st.

Effective/applicability date. This section applies to any tax year beginning on or after December 21, 2009. However, taxpayers may apply this section to any Federal income tax return filed on or after December 21, 2009. For tax years beginning before December 21, 2009, see § 1.1561-3T as contained in 26 CFR part 1 in effect on April 1, 2009.