具體計算公式要Google一下。一般分為以下兩種

Your Social Security income can be affected if you receive a pension from work not covered by Social Security. This is primarily due to two rules:

1. Windfall Elimination Provision (WEP): The WEP can reduce your Social Security retirement or disability benefits if you receive a pension from an employer who did not withhold Social Security taxes from your salary, such as a government agency or an employer in another country. The WEP affects how your Social Security benefit is calculated, potentially resulting in a lower benefit amount. The formula used to calculate Social Security benefits is modified, reducing the percentage of your average indexed monthly earnings (AIME) that is converted into your benefit.

2. Government Pension Offset (GPO): The GPO affects your Social Security spousal or survivor benefits if you receive a pension from a federal, state, or local government based on work where you did not pay Social Security taxes. If you're entitled to Social Security benefits as a spouse or widow/widower but also receive a government pension, the GPO may reduce your Social Security benefits by two-thirds of your government pension. In some cases, this can completely eliminate your Social Security spousal or survivor benefit.