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.

The law will increase benefits for millions of retirees, but it's still not clear where the added funds will come from.

The Social Security Fairness Act is set to transform retirement benefits for three million public sector retirees in the United States. With its recent approval by Congress, this legislation awaits the signature of President Joe Biden,