On January 1. Year 1, the Houston Corporation made amendments to its defined pension plan, resulting in 150,000 of past service costs. The plan has 100 active employees, of which 60 are vested and the remaining 40 will be vested in three years. There currently are no retirees under the plan. Houston has determined the following information regarding the past service costs: Unrecognized past service costs applicable to: Vested employees $60.000 Unvested employees $120,000 Total unrecognized past service costs $180,000 The aggregate number of future service years of employees expected to receive benefits is 500 years. Required: Determine the amount of past service costs to be amortized in Year 1 and subsequent ears under (a) IFRS and (b) U.S.GAAP