Prohibition on benefit increases while sponsor is in bankruptcy.—

A trust which is part of a plan to which this paragraph applies shall not constitute a qualified trust under this section if an amendment to such plan is adopted while the employer is a debtor in a case under title 11, United States Code, or similar Federal or State law, if such amendment increases liabilities of the plan by reason of—

(i) any increase in benefits,

(ii) any change in the accrual of benefits, or

(iii) any change in the rate at which benefits become nonforfeitable under the plan,

with respect to employees of the debtor, and such amendment is effective prior to the effective date of such employer’s plan of reorganization.

This paragraph shall not apply to any plan amendment if—

(i) the plan, were such amendment to take effect, would have a funding target attainment percentage (as defined in section 430(d)(2)) of 100 percent or more,

(ii) the Secretary determines that such amendment is reasonable and provides for only de minimis increases in the liabilities of the plan with respect to employees of the debtor,

(iii) such amendment only repeals an amendment described in section 412(d)(2), or

(iv) such amendment is required as a condition of qualification under this part.

For purposes of this paragraph, the term “employer” means the employer referred to in section 412(b)(1), without regard to section 412(b)(2).