Social Security does not look at how disabled you are, how many dependents you have, or how much you need each month when it sets your SSDI payment. It runs a fixed math formula on your lifetime earnings record. The Social Security Administration takes your 35 highest-earning years, adjusts each year's earnings for wage growth, averages them into a monthly figure called the Average Indexed Monthly Earnings (AIME), then applies a three-tier formula with fixed dollar breakpoints, called bend points, to convert that average into your Primary Insurance Amount (PIA), which is your monthly SSDI check. For 2026, those bend points are $1,286 and $7,749.
This article walks through exactly how that calculation works, step by step, with the current 2026 numbers. If you want to know what the average or maximum SSDI payment looks like by state, see our guide to SSDI average benefit amounts by state. If you are already receiving SSDI and want to know how much you can earn from work without losing your benefit, see SSDI SGA threshold and income limits for 2026. This page covers neither of those. It covers the formula itself.
The Three-Step Calculation SSA Actually Runs
Every SSDI benefit amount comes from the same three-step process, regardless of your condition, age, or state of residence.
- Pull your covered earnings history. SSA looks at every year you paid Social Security (FICA) taxes on wages or self-employment income, going back to age 22 (or the start of your work history if later).
- Index those earnings and average the top 35 years into an AIME. Older earnings get multiplied up to account for national wage growth, so a $20,000 salary in 1998 counts for more than the raw dollar figure once indexed to today's wage levels.
- Run the AIME through the PIA bend-point formula. This applies three different replacement rates to three slices of your AIME, which produces your Primary Insurance Amount, the base monthly figure your SSDI payment is built from.
Each step is worth breaking down in detail, because small differences in earnings history produce real differences in the final check.
Step 1: Your Covered Earnings Record
SSA maintains a year-by-year record of your taxed earnings under your Social Security number. This is the same record used for retirement benefits. Only earnings that had Social Security taxes withheld count. Under-the-table income, most government pension work not covered by Social Security, and income earned before age 22 typically don't factor in.
For SSDI specifically, the calculation uses a shortened, indexed earnings period rather than a strict lifetime average. SSA freezes your earnings record at the point your disability began (called the "date of onset"), so years after you stopped working due to disability don't count against you or drag your average down. This is one of the few places where SSDI's calculation differs meaningfully from retirement benefits, where the full working life through retirement age is generally used.
Step 2: Indexing and the AIME
Wages from decades ago are worth less in today's dollars, so SSA doesn't just average your raw historical earnings. It indexes each year's earnings to account for the growth in the national average wage since that year, using a published index factor for each year of your work history. Earnings in the last few years before your disability onset (typically the year you turn 60 and later, depending on your specific case) are not indexed and are counted at face value.
Once every year is indexed, SSA:
- Selects your 35 highest-earning years (indexed values), counting zeros for any year you didn't work if you have fewer than 35 years of covered earnings
- Adds those 35 years together
- Divides the total by 420 (the number of months in 35 years)
- Rounds down to the next lower dollar
That result is your AIME.
This is why work history length matters as much as income level. Someone who earned $70,000 a year for 20 years and then had 15 years of zero earnings will have a lower AIME than someone who earned $70,000 a year for a full 35 years, even though their peak earnings were identical. Every zero year gets averaged in and pulls the total down. This is also why fewer than 35 years of covered work almost always means a lower payment than the formula's structure would otherwise produce.
Step 3: The PIA Bend-Point Formula (2026 Figures)
Once SSA has your AIME, it applies the PIA formula. This formula is progressive by design. It replaces a much larger share of income for lower earners than for higher earners, which is why two people with very different lifetime earnings can end up with SSDI checks that are closer together than their salaries were.
For workers who become disabled in 2026, the formula is:
| AIME Bracket | Replacement Rate |
|---|
| First $1,286 of AIME | 90% |
| $1,286 up to $7,749 of AIME | 32% |
| Above $7,749 of AIME | 15% |
The dollar figures ($1,286 and $7,749) are the 2026 bend points. They are not fixed forever. SSA recalculates them every year based on the national average wage index, so someone who becomes disabled in 2027 will have slightly different bend points applied to their own AIME. Your bend points are locked in based on the year you first became eligible for benefits, not the year you're currently receiving them, so a COLA increase later doesn't change which bend points originally applied to your calculation, it just increases your payment amount going forward.
The total from all three brackets is added together and rounded down to the nearest dime. That total is your Primary Insurance Amount, which becomes your full monthly SSDI benefit before any offsets (such as workers' compensation) are applied.
Worked Example
Say a worker's AIME comes out to $4,000 per month. Here is how the 2026 formula processes that figure:
| Bracket | Calculation | Subtotal |
|---|
| 90% of first $1,286 | $1,286 × 0.90 | $1,157.40 |
| 32% of $1,286 to $4,000 | ($4,000 − $1,286) × 0.32 | $868.48 |
| 15% of amount above $7,749 | $0 (AIME didn't reach this bracket) | $0.00 |
| Total PIA | | $2,025.88, rounded to $2,025.80 |
That $2,025.80 is the worker's monthly SSDI benefit before any COLA adjustments applied after their eligibility year, and before any reductions for things like workers' compensation offset.
Notice how much of the benefit comes from the first bracket. The 90% rate on the first $1,286 alone contributes over half of this worker's total benefit, even though that bracket represents less than a third of their AIME. This is the progressive design at work: lower earners get a much higher percentage of their pre-disability income replaced than higher earners do.
Why Your Statement Estimate and Your Real Payment Can Differ
Your Social Security Statement, available at ssa.gov, shows an estimated disability benefit based on your current earnings record projected forward. That estimate assumes you keep earning at a similar rate until you become disabled. If your disability occurs earlier than expected, or your earnings pattern changes (a period of unemployment, a career change, a pay cut), your actual AIME and resulting PIA will differ from the projection. The formula itself doesn't change. What changes is the earnings history you feed into it.
What Can Reduce Your PIA Below What the Formula Produces
The bend-point formula produces your full, unreduced monthly benefit. Several factors can lower what you actually receive:
- Workers' compensation or public disability benefit offset. If your combined SSDI and other disability benefits exceed 80% of your average current earnings before disability, SSA reduces your SSDI payment to bring the total down to that cap.
- Family maximum limits. If your spouse or children also receive auxiliary benefits on your record, the total paid to your family is capped, and the family maximum can reduce individual payments if the cap is reached.
- Overpayment recovery. If SSA previously overpaid you, they may withhold a portion of your monthly check until the overpayment is repaid.
None of these change your PIA calculation itself. They apply after the PIA formula runs.
Once your PIA is calculated, a separate question is when that money actually shows up and in what form. For the five-month waiting period, what your first payment includes, and direct deposit versus Direct Express, see SSDI payment amount 2026: how it works.
What Can Increase Your Payment After the PIA Is Set
Once your PIA is established, a few things can raise your monthly check going forward:
- Annual COLA adjustments. Every SSDI recipient's payment increases by the same percentage each year that Congress and SSA apply a cost-of-living adjustment, regardless of when they became eligible.
- Additional work after your award, in limited cases. Generally, once your PIA is set at your date of onset, later earnings don't recalculate it upward the way they would for a retirement benefit, since your earnings record is frozen at disability onset for the initial calculation.
Frequently Asked Questions
What is AIME in SSDI calculations?
AIME stands for Average Indexed Monthly Earnings. It's calculated by taking your 35 highest-earning years of Social Security covered wages, adjusting each year's earnings for national wage growth, adding them together, and dividing by 420 months. It's the single input that feeds into the PIA bend-point formula.
What are Social Security bend points?
Bend points are the fixed dollar thresholds SSA uses to divide your AIME into brackets that get different replacement rates in the PIA formula. For 2026, the bend points are $1,286 and $7,749. AIME up to the first bend point is replaced at 90%, the amount between the two bend points is replaced at 32%, and any amount above the second bend point is replaced at 15%.
Does SSDI use my highest 35 years of earnings like retirement benefits?
Yes, the same 35-year averaging method applies to both. The key difference is that SSDI freezes your earnings record at your disability onset date, so you're not penalized for years you couldn't work due to your disability. Retirement benefits generally use your earnings up through the year before you start collecting.
What if I have fewer than 35 years of covered earnings?
SSA still divides by 420 months, but any missing years are counted as zero earnings in the average. This typically produces a lower AIME, and therefore a lower monthly benefit, than if you had a full 35-year work history at the same income level.
Do bend points change every year?
Yes. SSA adjusts the bend points annually based on the national average wage index. However, the specific bend points that apply to your benefit are locked in based on the year you first became eligible (generally the year your disability began), not the current year.
Can I calculate my exact SSDI payment myself?
You can approximate it using your Social Security Statement's earnings record and the formula above, but exact calculations require SSA's full indexing tables for every year of your work history. The estimate on your official Statement, or an estimate SSA provides during your claim, will be more precise than a manual calculation.
Does my disability severity affect how much my SSDI check is?
No. Once you're found medically disabled and meet the work credit requirements, the severity of your condition does not change your payment amount. Your monthly benefit is based entirely on your earnings history and the PIA formula, not on your diagnosis or how limited your daily functioning is.
