Social Security looks at your highest 35 years of earnings, not your most recent ones

When Social Security calculates how much you receive in SSDI each month, it does not use your current income or your income from last year. Instead, it reaches back through your entire work history and picks your 35 highest-earning years. The agency then averages those 35 years together to arrive at a number called your Primary Insurance Amount, or PIA. This is the foundation of your monthly benefit.

The reason Social Security uses 35 years is historical—it assumes most people work for roughly 35 years between age 22 and age 60. If you have worked fewer than 35 years, Social Security counts the missing years as zeros, which lowers your average. This is one reason why people who took time out of the workforce—for caregiving, education, or other reasons—often see a lower benefit than they might expect.

The calculation happens in steps. First, Social Security identifies every year you earned wages or were self-employed. Then it adjusts those older earnings upward using a formula tied to national wage growth, so that a dollar you earned in 1995 is not compared directly to a dollar you earned in 2020. After that adjustment, the agency selects your 35 best years and divides the total by 420 months (35 years × 12 months). The result is your average indexed monthly earnings, or AIME.

Key Takeaways

  • Social Security uses your 35 highest-earning years to calculate your benefit, regardless of when those years occurred in your work history.
  • If you worked fewer than 35 years, the missing years count as zero earnings and reduce your average benefit amount.
  • Older earnings are adjusted upward using a wage-growth formula so they can be fairly compared to more recent years.
  • Your average indexed monthly earnings (AIME) is then converted to your Primary Insurance Amount using a benefit formula that gives more weight to lower earners.

Why the 35-year window matters if you have gaps in work

If you took five years off to raise children, pursue education, or handle a health issue, Social Security still counts those five years in the 35-year average—but as zero dollars. This can significantly reduce your benefit. For example, if your 30 highest-earning years averaged $3,000 per month, but you have five zero years, your 35-year average drops to roughly $2,571 per month before the benefit formula is applied.

Social Security does offer one exception: the dropout years rule. If you have enough work credits to be insured for disability (generally 40 credits, with at least 20 earned in the 10 years before you became disabled), you may be able to exclude up to five years of low or zero earnings from your calculation. This is automatic—you do not request it. The agency straightforward removes your five lowest-earning years before calculating your average. If you have fewer than five low years, it removes only what you have.

The dropout rule can make a real difference. In the example above, if you could drop five zero years, your average would be based only on your 30 highest years, raising your average back to $3,000 per month. However, the dropout rule applies only to people who meet the work-credit requirement for disability. If you do not have enough credits, the zero years stay in the calculation.

How the benefit formula converts your average into a monthly payment

Once Social Security has calculated your AIME, it applies a benefit formula to convert that average into your Primary Insurance Amount. The formula is progressive, meaning it replaces a higher percentage of earnings for people who earned less. This is why two people with very different work histories can end up with different benefit amounts even if their AIME is the same.

The formula has three "bend points"—dollar thresholds that change each year. For 2024, the bend points are $1,174 and $7,078 (these numbers change annually based on national wage growth). Social Security applies a different percentage to earnings in each bracket. Earnings up to the first bend point are replaced at 90 percent. Earnings between the first and second bend point are replaced at 32 percent. Earnings above the second bend point are replaced at 15 percent.

Here is a concrete example: if your AIME is $2,500, Social Security would calculate your PIA as follows: ($1,174 × 0.90) + (($2,500 − $1,174) × 0.32) = $1,057.20 + $425.12 = $1,482.32. That $1,482.32 is your Primary Insurance Amount, and it becomes your monthly SSDI benefit (before any family members' benefits are considered).

What happens if you continue working while receiving SSDI

Your SSDI benefit is based on your historical earnings, not your current income. Once you are approved and receiving benefits, Social Security does not recalculate your benefit based on new work you do. However, there are limits on how much you can earn while on SSDI without losing benefits.

During the first nine months of work after you start SSDI, you can earn as much as you want without losing any benefits. This period is called the trial work period. After that, if you earn more than the monthly earnings limit (which varies by year but was $1,550 in 2024), you lose one dollar in benefits for every two dollars you earn above that limit. This continues until you either drop below the limit or your benefits end.

If you return to substantial work and your benefits stop, you enter an extended may be able to access period lasting 36 months. During this time, you can have months where you earn below the limit and receive a full benefit check, without restarting the process process. After 36 months, if you are still working above the limit, your benefits end permanently—though you may be able to reapply later if your work situation changes.

How your work history affects your family members' benefits

If you receive SSDI, your spouse and children may also receive benefits based on your work record. Their benefits are calculated as a percentage of your Primary Insurance Amount. A spouse at full retirement age receives 50 percent of your PIA. A spouse caring for a child under 16 receives 75 percent. Each child receives 75 percent. However, there is a family maximum: the total amount paid to you and all family members cannot exceed 150 to 180 percent of your PIA, depending on your situation.

This means that if you have a high PIA, your family members' individual benefits may be reduced so the total stays within the family maximum. The reduction is applied to family members' benefits, not to yours. Understanding this matters if you are considering work that might affect your benefit, because changes to your benefit ripple through to your family members' payments as well.

Recalculation and cost-of-living adjustments after you start receiving benefits

Your Primary Insurance Amount does not change just because you continue to work or earn more money after you start SSDI. However, Social Security does recalculate your benefit once per year if you continue working and earning. This recalculation uses the same 35-year averaging method, but now includes your new earnings year. If your new year of earnings is high enough to replace one of your previous 35 years, your AIME and PIA increase.

Additionally, every January, Social Security adjusts all SSDI benefits by a cost-of-living adjustment, or COLA. This adjustment is the same percentage for everyone and is based on inflation measured by the Consumer Price Index. In 2024, the COLA was 3.2 percent. This adjustment applies to your PIA and automatically increases your monthly check, but it is separate from any recalculation based on new work.

Frequently Asked Questions

What if I did not work for 35 years—will my benefit be much lower?

Yes, it will be lower than someone with 35 years of high earnings. Social Security counts missing years as zero. However, if you have enough work credits for disability (generally 40 credits), you may be able to drop up to five of your lowest-earning years, which can help. The exact reduction depends on how many years you worked and how much you earned in those years.

Can I see which 35 years Social Security is using to calculate my benefit?

Yes. Create an account on ssa.gov and view your Social Security Statement. It shows your earnings record year by year and indicates which years are being used in your calculation. You can also call Social Security at 1-800-772-1213 to request a detailed breakdown of your benefit calculation.

If I earn more money next year, will my SSDI benefit go up?

It may. Social Security recalculates your benefit once per year if you are working. If your new earnings are high enough to replace one of your lowest 35 years, your average goes up and your benefit increases. However, if you earn above the monthly limit, you will lose benefits during the months you are over the limit, even if your long-term benefit amount increases.

Does my spouse's work history affect my SSDI benefit?

No. Your SSDI benefit is based only on your own work record and earnings history. Your spouse's earnings do not change your benefit. However, your spouse may be able to receive their own SSDI benefit based on their own work record if they also have a disability and enough work credits.

What is the difference between my Primary Insurance Amount and my actual monthly check?

Your Primary Insurance Amount is the base benefit calculated from your earnings history. Your actual monthly check may be different if you have family members receiving benefits on your record (their benefits reduce the family maximum, which can reduce yours) or if you are in a trial work period or extended may be able to access period. It may also be reduced if you are receiving workers' compensation or certain government pensions.