Biden estimated the bill should lead to an average monthly increase of $360 for certain public employees and their spouses and survivors. The outgoing president said more than 2.5 million Americans will receive a lump sum payment worth "thousands of dollars" to compensate for the benefits they should have received last year.

For decades, Americans have seen lower Social Security checks if they fall into the circumstances under the WEP and GPO.

A previous law from the 1980s has prevented many workers with public service jobs from being able to receive Social Security benefits, despite paying into the system.