In general
In the taxable year when paid, if the contributions are paid into a pension trust (other than a trust to which paragraph (3) applies), and if such taxable year ends within or with a taxable year of the trust for which the trust is exempt under section 501(a), in the case of a defined benefit plan other than a multiemployer plan, in an amount determined under subsection ( o ), and in the case of any other plan in an amount determined as follows:
(i)#
the amount necessary to satisfy the minimum funding standard provided by section 412(a) for plan years ending within or with such taxable year (or for any prior plan year), if such amount is greater than the amount determined under clause (ii) or (iii) (whichever is applicable with respect to the plan),
(ii)#
the amount necessary to provide with respect to all of the employees under the trust the remaining unfunded cost of their past and current service credits distributed as a level amount, or a level percentage of compensation, over the remaining future service of each such employee, as determined under regulations prescribed by the Secretary, but if such remaining unfunded cost with respect to any 3 individuals is more than 50 percent of such remaining unfunded cost, the amount of such unfunded cost attributable to such individuals shall be distributed over a period of at least 5 taxable years,
(iii)#
an amount equal to the normal cost of the plan, as determined under regulations prescribed by the Secretary, plus, if past service or other supplementary pension or annuity credits are provided by the plan, an amount necessary to amortize the unfunded costs attributable to such credits in equal annual payments (until fully amortized) over 10 years, as determined under regulations prescribed by the Secretary.
In determining the amount deductible in such year under the foregoing limitations the funding method and the actuarial assumptions used shall be those used for such year under section 431, and the maximum amount deductible for such year shall be an amount equal to the full funding limitation for such year determined under section 431.