Social Security Questions? Ask a Social Security Expert
the Government Pension Offset (GPO), reduces Social Security benefits paid to spouses or survivors when the spouse or survivor earned a pension from a government job that was not covered by Social Security. The GPO reduction is equal to two-thirds of the amount of the pension payment from noncovered government work.
The state may not "opt out" of the GPO provision - that is a federal law.
The Government Pension Offset ensures that the SSA calculate the benefits of government employees who don’t pay Social Security taxes the same as workers in the private sector who pay Social Security taxes.
See some details here
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