President Joe Biden signed a bill Sunday that boosts Social Security benefits for millions of public sector workers in what the White House described as the first expansion of such benefits in 20 years. 

The Social Security Fairness Act eliminates two decades-old provisions — the Windfall Elimination Provision and the Government Pension Offset — that reduced Social Security benefits for some retirees who also received pension income. Police officers, firefighters, postal workers, and public school teachers are among the nearly 3 million affected by the provisions.  

"The bill I'm signing today is about a simple proposition: Americans who have worked hard all their lives to earn an honest living should be able to retire with economic security and dignity," Biden said.  

Social Security Fairness Act:Congress approves changes to Social Security for some public sector workers

Biden said the bill should lead to an estimated average monthly increase of $360 for certain public employees and their spouses and survivors. More than 2.5 million Americans are set to receive a lump sum payment worth "thousands of dollars" to make up for the shortfall and the benefits they should have received last year, Biden said.  

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The bill, passed by the House of Representatives in November, was approved in the Senate by a 70-26 vote last month. Some senators who voted against the legislation argued it would unfairly benefit some workers while increasing burdens for others on Social Security, and jeopardize the Social Security fund overall.

The bill will cost $196 billion over the next 10 years, according to estimates by the Congressional Budget Office.

Contributing: Riley Beggin and Medora Lee, USA TODAY; Reuters