The Basic Formula: Primary Insurance Amount and Your Work History

Social Security calculates your SSDI payment using a formula based on your Primary Insurance Amount (PIA), which is derived from your lifetime earnings record. The agency does not use a fixed dollar amount for everyone — your payment depends on how much you earned during your working years and how long you worked.

The calculation starts with your Average Indexed Monthly Earnings (AIME). Social Security takes your 35 highest-earning years (or fewer if you have not worked 35 years), adjusts those earnings for inflation using a national wage index, and divides the total by 420 months. This produces your AIME. If you worked fewer than 35 years, the missing years count as zero, which lowers your AIME and your final payment.

Once Social Security has your AIME, it applies a bend point formula to calculate your PIA. The bend points are dollar thresholds that change each year. For 2024, the formula takes 90 percent of your first $1,174 in AIME, then 32 percent of AIME between $1,174 and $7,078, then 15 percent of anything above $7,078. The sum of those three amounts is your PIA — your full monthly benefit at full retirement age.

Key Takeaways

  • Your SSDI payment is based on your own earnings record, not on how disabled you are or how much money you need.
  • Social Security uses your 35 highest-earning years; years you did not work count as zero and reduce your payment.
  • The bend point formula gives you a higher percentage of your first dollars earned and a lower percentage of higher earnings.
  • Your payment amount is set when you are approved and increases each year with the cost-of-living adjustment (COLA).
  • Family members may receive payments based on your record, which does not reduce your own payment but may trigger a family maximum.

How Your Earnings Record Affects the Calculation

Social Security pulls your earnings record from the taxes you and your employers paid into the system. If you worked under different names or Social Security numbers, gaps may appear in your record. You can request a copy of your earnings record through your my Social Security account or by calling 1-800-772-1213 to verify it is correct before your claim is processed.

Years you did not work — whether due to unemployment, caregiving, or other reasons — are included as zero-earnings years in the calculation. If you have fewer than 35 years of earnings, those zero years pull down your AIME and your final payment. This is why someone who worked 30 years receives a lower payment than someone who worked 40 years, even if both earned the same amount per year.

Self-employment income counts toward your record if you reported it on your tax return. If you underreported or did not report self-employment income, your SSDI payment will be lower than it should be. You can file an amended tax return (Form 1040-X) to correct past years, though Social Security can only go back a limited number of years.

The Bend Point Formula and Why It Matters

The bend point formula is designed to replace a higher percentage of earnings for lower-income workers and a lower percentage for higher-income workers. This means two people with very different earnings histories will not receive proportionally different payments.

For example, under the 2024 bend points, someone with an AIME of $2,000 receives 90 percent of the first $1,174 ($1,056.60) plus 32 percent of the remaining $826 ($264.32), totaling $1,320.92. Someone with an AIME of $4,000 receives 90 percent of $1,174 ($1,056.60) plus 32 percent of $5,826 ($1,864.32) plus 15 percent of $0, totaling $2,920.92. The second person earned twice as much but receives only 2.2 times the payment.

Bend points change each year based on the national average wage index. Social Security publishes new bend points in October for claims filed in the following year. If you are trying to estimate your payment, use the current year's bend points, but understand that the actual calculation will use the bend points in effect when you file.

Cost-of-Living Adjustments (COLA) and Payment Changes

Once Social Security approves your claim and sets your PIA, your payment does not stay fixed. Each year in October, Social Security announces a cost-of-living adjustment (COLA) that increases all SSDI payments by a percentage tied to inflation. In 2024, the COLA was 3.2 percent; in 2023, it was 8.7 percent. The adjustment varies year to year based on the Consumer Price Index.

Your payment increases automatically in January following the COLA announcement — you do not need to request it or reapply. The new amount appears in your January payment and in your updated benefit statement. If you are receiving payments for family members based on your record, their payments increase by the same percentage.

COLA does not explore to Supplemental Security Income (SSI), which is a separate program for people with low income and few resources. If you receive both SSDI and SSI, only your SSDI portion increases with COLA.

Family Payments and the Family Maximum

If you are receiving SSDI, your spouse, ex-spouse, and children may also receive payments based on your earnings record. Each family member receives a percentage of your PIA — typically 50 percent for a spouse at full retirement age, 75 percent for a child, and 50 percent for a spouse caring for a child under 16. These payments do not reduce your own SSDI payment.

However, there is a family maximum, usually between 150 and 180 percent of your PIA. If the total of all family members' payments would exceed this maximum, Social Security reduces each family member's payment proportionally (your payment is never reduced). For example, if your PIA is $1,500 and the family maximum is 175 percent ($2,625), and your spouse and two children would each receive $750, the total would be $3,000. Social Security would reduce each family member's payment to stay within the $2,625 cap.

The family maximum applies only to family members receiving on your record. It does not affect your own payment or any benefits they may receive on their own work record.

What Happens If You Worked in Other Countries

If you worked and paid Social Security taxes in the United States, those earnings count toward your SSDI calculation regardless of where you currently live. If you worked in another country, those earnings generally do not count toward your U.S. Social Security record unless that country has a totalization agreement with the United States.

The United States has totalization agreements with about 30 countries, including Canada, the United Kingdom, Germany, France, and others. Under these agreements, you can combine work credits from both countries to meet the insured status requirement for SSDI. However, the actual payment calculation uses only your U.S. earnings. If you worked in a country with a totalization agreement, contact Social Security to discuss how your foreign work may affect your claim.

Frequently Asked Questions

Can I see what my SSDI payment will be before I file?

Yes. Log into your my Social Security account and view your benefit estimate, which shows your projected payment at different ages. You can also call 1-800-772-1213 to request an estimate by phone. The estimate uses your current earnings record and bend points, so it may change if you work more before you file or if bend points change.

What if there are gaps or errors in my earnings record?

Request a copy of your earnings record through my Social Security or by mail. If you find errors, file a correction with Social Security as soon as possible, ideally before you file for SSDI. Corrections can take several months, so do not wait until you have already applied. Bring W-2s or tax returns as proof of the correct earnings.

Does my SSDI payment change if I work while receiving benefits?

Your SSDI payment itself does not change based on current work. However, if you work and earn above the substantial gainful activity (SGA) limit — $1,550 per month in 2024 — Social Security may determine you are no longer disabled and stop your benefits. Any new earnings also become part of your record for future benefit calculations, which could increase your payment if those years are higher than some of your previous 35 years.

How much will my family members receive?

Each family member receives a percentage of your PIA: typically 50 percent for a spouse at full retirement age, 75 percent for a child, and 50 percent for a spouse caring for a child under 16. The family maximum caps the total at 150 to 180 percent of your PIA. Social Security will calculate the exact amounts when you file and provide them in your approval notice.

Will my payment increase if I delay filing?

SSDI payments do not increase for delaying — your PIA is set based on your age and earnings record when you file. This is different from retirement benefits, which increase if you delay past full retirement age. File for SSDI as soon as you meet the medical and non-medical requirements.