The Basic Formula: Primary Insurance Amount and Your Work History

Social Security calculates your SSDI benefit using a formula based on your Primary Insurance Amount (PIA), which itself depends on your average earnings over your highest-earning years. The agency does not use a single percentage or flat calculation—instead, it averages your covered earnings, adjusts them for inflation, and then applies a bend-point formula that pays a higher percentage on lower earnings and a lower percentage on higher earnings.

The first step is determining your Average Indexed Monthly Earnings (AIME). Social Security takes your 35 highest-earning years (or fewer if you have not worked that long), indexes those earnings to account for wage growth, and divides the total by 420 months. This number becomes the base for everything that follows. If you have worked fewer than 35 years, the agency includes zeros for the missing years, which lowers your average.

Once Social Security has your AIME, it applies the bend-point formula. In 2025, the formula uses two bend points—dollar amounts that change each year. For 2025, those bend points are $1,174 and $7,078. The formula pays 90 percent of your AIME up to the first bend point, 32 percent of the amount between the first and second bend point, and 15 percent of anything above the second bend point. The sum of those three amounts is your PIA, which is your full SSDI benefit at your full retirement age (though SSDI does not use retirement age the same way—your benefit is based on disability, not age).

Key Takeaways

  • Your SSDI benefit is calculated from your 35 highest-earning years, indexed for inflation, then divided by 420 months to create your Average Indexed Monthly Earnings.
  • The bend-point formula pays you a higher percentage of your lower earnings and a lower percentage of your higher earnings, which means lower-wage workers receive a larger percentage of their past earnings as a benefit.
  • The bend points change every year with the national wage index, so the same work history produces a different benefit amount in 2025 than it did in 2024.
  • Your actual monthly payment may be lower than your PIA if you receive other benefits, such as workers' compensation or a government pension, due to offset rules.
  • You can request a detailed earnings record from Social Security to verify the years and amounts they are using in your calculation.

How Bend Points Work and Why They Matter

The bend-point formula is the reason SSDI replaces a larger percentage of earnings for lower-wage workers than for higher-wage workers. If you earned very little over your career, Social Security replaces roughly 90 percent of that average. If you earned a high income, the replacement rate drops to around 15 percent on the portion above the second bend point. This is intentional: the program is designed to provide a basic income floor rather than to maintain your pre-disability standard of living dollar-for-dollar.

The bend points themselves are adjusted annually based on the national average wage index. In 2024, the first bend point was $1,174 and the second was $7,078. In 2025, those figures may shift slightly. You can find the exact 2025 bend points on the Social Security Administration website, but the change is usually small—typically a few dollars. What matters is that your AIME is compared against these thresholds, and each portion of your earnings is multiplied by its corresponding percentage.

Example: If your AIME is $2,000, Social Security would calculate your PIA as follows: 90 percent of $1,174 ($1,056.60) plus 32 percent of the amount between $1,174 and $2,000, which is $826 times 0.32 ($264.32), for a total PIA of $1,320.92. That would be your monthly benefit before any reductions.

Adjustments That Reduce Your Calculated Benefit

Your calculated PIA is not always the amount you receive each month. Several rules can lower your payment. The most common is the Government Pension Offset (GPO), which applies if you receive a pension from work where you did not pay Social Security taxes—typically government employment. The GPO reduces your SSDI benefit by two-thirds of that pension amount. If your pension is $900 per month, the GPO reduces your SSDI by $600.

Another reduction is the Windfall Elimination Provision (WEP), which also affects people with government pensions or non-covered work. The WEP changes the bend-point formula itself, using a different (lower) percentage on the first bend point, which can reduce your benefit by up to 50 percent of the non-covered pension. Unlike the GPO, the WEP modifies the calculation rather than subtracting from the result.

If you receive workers' compensation or certain other public disability benefits, Social Security may reduce your SSDI so that the combined total does not exceed 80 percent of your average current earnings before you became disabled. This is called the workers' compensation offset. The reduction applies to your SSDI payment, not to the workers' compensation itself.

How Earnings Records Affect Your Calculation

Your SSDI benefit is only as accurate as the earnings record Social Security has on file. The agency uses W-2 forms and self-employment tax returns to build this record. If you worked under a different name, had unreported income, or if your employer reported earnings incorrectly, your record may be incomplete or wrong. This directly lowers your AIME and therefore your benefit.

You can request a Statement of Earnings from Social Security to see exactly which years and amounts the agency is using. You have the right to correct errors on this record, but you must do so within a specific timeframe—generally three years, three months, and 15 days from the end of the year in which the earnings were reported. If you spot an error, contact Social Security with documentation (old W-2s, pay stubs, or tax returns) and request a correction.

If you worked for multiple employers in a single year, make sure all of them reported your earnings. If you were self-employed, verify that your Schedule C income was reported correctly. Missing or understated earnings in even one year can reduce your AIME and lower your lifetime benefit.

Family Benefits and How They Relate to Your Calculation

Your SSDI benefit is calculated based on your own work record, but family members may also receive benefits based on that same record. Your spouse, ex-spouse, and children under 19 (or 19 if still in high school) may each receive up to 50 percent of your PIA. However, there is a family maximum: the total amount paid to all family members cannot exceed 150 to 180 percent of your PIA, depending on your situation.

When family members receive benefits, your own benefit does not change—the family maximum applies to the total pool, not to your individual payment. If your PIA is $1,500 and the family maximum is $2,250, and your spouse and two children are also receiving benefits, the four of you share that $2,250 total. Your payment stays $1,500, but the other three receive less than they would if the family maximum did not exist.

Cost-of-Living Adjustments and Annual Changes

Your SSDI benefit is adjusted each year by a Cost-of-Living Adjustment (COLA), which is based on the Consumer Price Index. The COLA is announced in October for the following year and takes effect in January. In recent years, COLA has ranged from 0 percent (in 2016) to 8.7 percent (in 2023). The 2025 COLA will be announced in October 2024.

The COLA applies to your PIA, not to the bend points or the formula itself. If your benefit was $1,500 in 2024 and the COLA is 3 percent, your 2025 benefit becomes $1,545. This adjustment happens automatically—you do not need to do anything. However, if you are subject to the GPO or WEP, the offset or reduction is recalculated each year as well, so your net payment may not increase by the full COLA percentage.

Frequently Asked Questions

Can I see how Social Security calculated my specific benefit amount?

Yes. Log into your my Social Security account online, or call 1-800-772-1213 to request a detailed benefit calculation statement. Social Security will show you the years used, the indexed earnings for each year, your AIME, and your PIA. If you disagree with any figure, you can request a correction with supporting documents.

Does working more years increase my SSDI benefit?

Yes, if your new earnings are higher than one of your current 35 highest-earning years. Social Security automatically recalculates your benefit each year to include the most recent year of earnings if it replaces a lower-earning year. However, if you are already receiving SSDI, your benefit does not increase retroactively—the new calculation takes effect the following January or when you return to work, depending on your situation.

What happens to my benefit if I worked part-time or had gaps in employment?

Gaps lower your AIME because Social Security includes zeros for years you did not work (up to 35 years total). Part-time work counts fully—the amount matters, not the hours. If you have fewer than 35 years of earnings, the zeros drag down your average. If you have more than 35 years, Social Security uses only your 35 highest-earning years, so very low-earning years are excluded.

If I am married, does my spouse's earnings affect my SSDI calculation?

No. Your SSDI benefit is based entirely on your own work record. Your spouse may receive a separate benefit based on their own record, or a spousal benefit based on yours (up to 50 percent of your PIA), but their earnings do not change your calculation. The two benefits are independent.

How do I know if the Government Pension Offset or Windfall Elimination Provision applies to me?

If you receive a pension from work where you did not pay Social Security taxes—such as federal, state, or local government employment—you may be subject to one or both. Contact Social Security directly with details of your government employment and pension. They will tell you whether an offset applies and by how much. You can also see this information in your my Social Security account under "Estimates" or "Benefits."