Social Security’s website provides a calculator to help you gauge the impact on your benefits from the Windfall Elimination Provision (WEP), the rule that reduces retirement benefits for workers who also collect a “non-covered” pension from a job in which they didn’t pay Social Security taxes. The provision affects about 2 million Social Security beneficiaries, most of them veterans of federal, state or local government service.
The WEP works by tweaking the formula Social Security uses to calculate your retirement benefit. This is done so people who worked primarily in non-covered jobs (and who thus have relatively little in their Social Security earnings record) do not get the same advantage from Social Security’s progressive benefit calculation as do longtime low-wage workers.
The amount of tweaking is determined by how many years you had “substantial earnings” from work in which you did pay Social Security taxes, perhaps from a part-time or second-career job in the private sector. (You can find out what Social Security considers substantial earnings in its WEP factsheet.)
The more years in which you met the "substantial earnings" test, the less the Windfall Elimination Provision takes out of your Social Security payments. If you have 30 or more such years, the WEP does not apply — there's no benefit reduction based on your pension.
To use the WEP calculator, plug in your date of birth, the age at which you claimed (or plan to claim) Social Security, your monthly pension payment, and annual earnings from years in which you did Social Security–covered work. The calculator will approximate your WEP-modified retirement benefit and, conveniently, what you or your surviving spouse and children would receive if you become disabled or die.
Keep in mind
By law, the Windfall Elimination Provision cannot cut your Social Security payment by more than half of the amount of your monthly pension, and it cannot zero out your retirement benefit.