An employer that is liable for 20-year-limitation amounts shall be liable to the plan for an amount equal to the present value of all initial withdrawal liability payments for which the employer was not liable pursuant to section 4219(c)(1)(B) of ERISA. The present value of such payments shall be determined as of the end of the plan year preceding the plan year in which the employer withdrew, using the assumptions that were used to determine the employer's payment schedule for initial withdrawal liability pursuant to section 4219(c)(1)(A)(ii) of ERISA. Any liability for 20-year-limitation amounts determined under this section shall be limited by section 4225 of ERISA to the extent that section would have been limiting had the employer's initial withdrawal liability been determined without regard to the 20-year limitation.