President Biden on Sunday signed into law a measure that boosts Social Security payments for nearly 3 million government workers who receive generous pensions from their time as teachers, firefighters, police officers and in other public service jobs.

Advocates say the Social Security Fairness Act rights a decades-old disparity, though it will also put strain on Social Security Trust Funds, which face a looming insolvency crisis.

While some Republicans such as Senator Collins supported the legislation, others, including Senator Thune, Senator Paul, and Senator Tillis, voted against it. “We caved to the pressure of the moment instead of doing this on a sustainable basis,” Mr. Tillis told The Associated Press.

The annual Social Security and Medicare trustees report released last May said the program’s trust fund will be unable to pay full benefits beginning in 2035. The new law will hasten the program’s insolvency date by about half a year, according to some estimates, and cut lifetime benefits by $25,000 for a typical couple retiring in 2033.

Budget hawks told the New York Sun last month that the bill — expected to cost $196 billion over the next ten years alone — is “dystopian” and “insane.” 

“The bill is not fiscally responsible. It’s not fair,” a senior fellow at the American Enterprise Institute focusing on Social Security reform, Andrew Biggs, said. “It’s not helping a group that’s in any need. Public employees have the most generous pensions in America. They’re a predominantly high-income group.

“In the case of spousal and survivor’s benefits, it would be possible for a state or local government employee who never paid any taxes to receive the Social Security benefit in addition to their own government pension benefit,” Mr. Biggs added. “That’s the sort of double dipping that you can’t do if both spouses participate in Social Security.”

The bill rescinds two provisions — the Windfall Elimination Provision and the Government Pension Offset — that limit Social Security benefits for recipients if they get retirement payments from other sources, including public retirement programs from a state or local government.

The Congressional Research Service estimated that in December 2023, there were 745,679 people, about 1 percent of all Social Security beneficiaries, who had their benefits reduced by the Government Pension Offset. About 2.1 million people, or about 3 percent of all beneficiaries, were affected by the Windfall Elimination Provision.

The Congressional Budget Office estimated in September that eliminating the Windfall Elimination Provision would boost monthly payments to the affected beneficiaries by an average of $360 by December 2025. Ending the Government Pension Offset would increase monthly benefits in December 2025 by an average of $700 for 380,000 recipients getting benefits based on living spouses, according to the CBO. The increase would be an average of $1,190 for 390,000 or surviving spouses getting a widow or widower benefit.

Those amounts would increase over time with Social Security’s regular cost-of-living adjustments.

The change is to payments from January 2024 and beyond, meaning the Social Security Administration would owe back-dated payments. The measure as passed by Congress says the Social Security commissioner “shall adjust primary insurance amounts to the extent necessary to take into account” changes in the law. It’s not immediately clear how this will happen or whether people affected will have to take any action.

Senator Brown, who pushed for the proposal for years, lost his reelection bid for one of Ohio’s Senate seats in November. Lee Saunders, president of the American Federation of State, County and Municipal Employees labor union, thanked Mr. Brown for his advocacy.

The future of Social Security has become a top political issue and was a major point of contention in the 2024 election. About 72.5 million people, including retirees, disabled people and children, receive Social Security benefits.

The policy changes from the new law will heap more administrative work on the Social Security Administration, which is already at its lowest staffing level in decades. The agency, currently under a hiring freeze, has a staff of about 56,645 — the lowest level in over 50 years even as it serves more people than ever.