26 U.S. Code § 194A - Contributions to employer liability trusts
In the case of a contribution described in subsection (a) which relates to any specified period of time which includes more than one taxable year, the amount properly allocable to any taxable year in such period shall be determined by prorating such amounts to such taxable years under regulations prescribed by the Secretary.
No deduction shall be allowed under subsection (a) with respect to any contribution described in subsection (a) which does not relate to any specified period of time.
Section 4223(h) of the Employee Retirement Income Security Act of 1974, referred to in subsec. (a), is classified to section 1403(h) of Title 29, Labor.