Example: The computation of the spouse tier I may be illustrated as follows: A railroad employee's wife who was born on September 16, 1920, becomes entitled to a spouse annuity on October 1, 1982. She is also entitled to a social security benefit of $190 a month effective October 1, 1982. Her husband's employee tier I PIA is $712.60. The spouse tier I is $356.30 (50 percent of $712.60). This is rounded down to $356. Since she is 35 months under age 65, the present retirement age when the annuity begins, $356 is multiplied by 35/144, to produce an age reduction of $86.53 and a tier I rate after age reduction of $269.47. Her final tier I rate effective October 1, 1982, after reduction for social security benefits, is $79.47 ($269.47 -$190.00).
20 C.F.R. §226.30