(NEXSTAR) – A law signed by former President Joe Biden in January is starting to show its impact, as millions of people begin to receive bigger Social Security payments plus back pay.

The change comes after the bipartisan Social Security Fairness Act was passed and signed into law in the final weeks of Biden’s term as president. The law rescinds measures that limited Social Security benefits for recipients if they got retirement payments from other sources, including public retirement programs from a state or local government.

As a result, about 3.2 million people who worked as police officers, firefighters, teachers and in other public service roles will now get larger Social Security payments. Because the change is effective dating back to January 2024, eligible recipients also get retroactively paid for the extra money they were missing out on for about the past year. The back-paid amount is expected to come in one lump-sum payout.

Who qualifies for the bigger payments?

The people impacted include some teachers, officers, firefighters, federal workers who were covered by the Civil Service Retirement System, and people who were covered by another country’s social security system, the Social Security Administration says.

That doesn’t mean every former teacher or cop will suddenly get more money, however.

“Most state and local public employees – about 72 percent – work in Social Security-covered employment where they pay Social Security taxes and are not affected by WEP or GPO,” the Administration explains, referring to the Windfall Elimination Provision and Government Pension Offset (the two measures recently repealed). “Those individuals will not receive a benefit increase due to the new law.”

Anyone who qualifies under the change will receive a notice in the mail explaining the new benefits, but some may receive the extra money before they receive a letter.

“Most people will receive their retroactive payment two to three weeks before they receive their notice in the mail, because the President understands how important it is to pay people what they are due right away,” the Administration says.

When do the increased payouts begin? When will the retroactive payment go out?

The one time retroactive payments started going out on Feb. 24, and will hit most people’s bank accounts by the end of March, the Administration says. The process is largely automated, but some more complex cases will need individual review, and those payments could come later.

The new, increased monthly payments will start in April.

How much bigger are the new payments?

It depends on the person, but there’s a pretty big range of possible outcomes. The Social Security Administration says some may see their monthly benefits increase “very little” while others could get $1,000 more.

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.

What should you do if you believe you qualify for increased payments, but don’t see any change?

The Social Security Administration asks people wait until after they receive their April monthly benefit before asking questions about the retroactive payment or the increased benefit amount. Frequently asked questions may be answered on the Social Security Fairness Act site.

The Associated Press contributed to this report.