Government Pension Offset Reform Act - Amends title II (Old Age, Survivors and Disability Insurance) (OASDI) of the Social Security Act to modify the formula for determining the amount of reduced monthly OASDI benefits payable to a spouse, surviving spouse, or parent receiving monthly payments from a federal or state pension plan. Declares that such benefit reductions shall be equal to the amount by which two-thirds of the total amount of the combined monthly benefit (before reduction) and monthly pension exceeds $1,200, adjusted for inflation.