SSDI and SSI Calculator (2026): Benefit and Back Pay

The SSDI Benefit Formula

Social Security Disability Insurance (SSDI) pays a benefit based on your earnings record, not on need. SSA first works out your average indexed monthly earnings (AIME): it adjusts each past year of earnings for wage growth, keeps your highest years, and averages them into a monthly figure. For disability, the number of years used depends on your age, with one year dropped for every five elapsed, up to five, under 20 CFR 404.211.

SSA then turns the AIME into your primary insurance amount (PIA) with a three-part formula. The dollar thresholds, called bend points, are set for the year your disability began. For 2026, SSA's Federal Register notice sets them at $1,286 and $7,749, so the PIA is:

• 90% of the first $1,286 of AIME, plus
• 32% of AIME between $1,286 and $7,749, plus
• 15% of AIME above $7,749.

The total is rounded down to the next lower dime under 20 CFR 404.212. Each December cost-of-living increase after that year is added and rounded down to the dime again (2.5% for December 2024, 2.8% for December 2025), and the monthly benefit is the result rounded down to a whole dollar under 20 CFR 404.304(f).

The formula is weighted toward lower earners: the first dollars of AIME are replaced at 90%, the last at 15%. That is why two people whose earnings differ a lot can end up with benefits that differ much less. Your my Social Security statement shows your earnings year by year and SSA's own disability estimate, and it is the best number to check this calculator against.

How SSDI Back Pay Is Counted

Three rules decide how many months of SSDI you are owed when a claim is approved. The back pay tab applies all three and shows each month.

• The five-month waiting period. Under 20 CFR 404.315, you must be disabled for five full consecutive calendar months, and benefits begin the month after that period ends (404.316). SSA's operations manual (POMS DI 10105.070) counts a month only if the onset date is on or before its first day. No waiting period applies if you were entitled to disability benefits within the prior five years, or if you have ALS.
• Twelve months of retroactivity. Under 20 CFR 404.621, a disability application can pay benefits for up to 12 months before the month you filed. The waiting period itself can start no earlier than the 17th month before the month you applied, so a very late application loses the months before that window.
• Up to the decision month. Past-due benefits are the benefits that built up "up to but not including the month the determination or decision is made" (20 CFR 404.1703).

Example: your disability began March 15, 2025, you applied in April 2025, and you were approved in February 2026. March does not count because you were not disabled the whole month, so the waiting period runs April through August 2025, benefits start in September 2025, and September 2025 through January 2026 is five months of back pay.

If you also received SSI for some of the same months, SSA reduces the SSDI back pay by the SSI it would not have paid had SSDI been paid on time, under 20 CFR 416.1123(d).

How SSI Is Figured

Supplemental Security Income (SSI) is need-based. It starts from the federal benefit rate, $994 a month for one person or $1,491 for an eligible couple in 2026 per the 2026 notice, and subtracts your countable income:

• The first $20 of most income in a month is not counted (20 CFR 416.1124(c)(12)); any unused part applies to earned income.
• From earned income, $65 more is not counted, then only half of what remains counts (20 CFR 416.1112(c)).
• A couple gets these exclusions once, not once each (POMS SI 00820.500).
• If you live in another person's household for the whole month, receive shelter from them, and others in the household provide all of your meals, SSA counts one-third of the federal rate as extra income instead of valuing the help (20 CFR 416.1131).

SSI has no retroactive months: it is payable starting the month after you filed, or the month after you first met every requirement if that came later (20 CFR 416.335, 416.330). An earlier protective filing date, set by a written statement or an inquiry before the application, can move the filing date back (20 CFR 416.340-416.350). Large past-due SSI amounts, counted after attorney fees and any repayment of state interim assistance, are generally paid in up to three installments six months apart (20 CFR 416.545). Many states add a supplement to SSI; the calculator leaves it out, and your state's Social Security disability page covers it along with how Medicaid works with SSI there.

Representative Fees

Disability attorneys and non-attorney representatives can be paid directly out of past-due benefits. Under the fee agreement process, the fee is limited to the lesser of 25% of past-due benefits or a dollar cap, which SSA raised to $9,200 effective November 30, 2024 (89 FR 40523) and kept in place in 2025 (90 FR 19241). For a combined SSDI and SSI claim, one limit covers both together. When SSA pays the representative directly, it deducts a user fee of 6.3% (up to $123 from December 2025) from the representative's fee. The calculator shows the fee-agreement limit on your estimate for information only.

What This Calculator Does Not Do

• It does not decide whether you are disabled or eligible. It does not apply SSA's five-step disability evaluation, the Listing of Impairments, work-credit (insured status) rules, or the SSI resource limits.
• It is not SSA's calculation. SSA works from your full earnings record. The AIME you enter, or the rough approximation, drives everything here.
• It leaves out family benefits for a spouse or children (it shows only an approximate family maximum), workers' compensation or public disability benefit offsets, state SSI supplements, overpayments, and any cost-of-living increase SSA has not yet announced.
• It does not apply SSI deeming. If you live with a spouse who is not eligible for SSI, are a child living with a parent, or are a noncitizen with a sponsor, SSA counts part of that person's income as yours (20 CFR 416.1160), which can lower the SSI payment a lot.
• It carries 2024 to 2026 figures. For a disability that began before 2024, enter the monthly amount from your SSA notice in the back-pay tab.

For the rules that do vary by state, including SSI supplements, Medicaid, and where hearings are held, start with Social Security disability by state. Veterans can compare VA compensation with the VA disability calculator; VA and SSDI are separate programs: under 20 CFR 404.1504 a VA disability decision is not binding on SSA, though SSA considers the evidence behind it.

This page is general legal information, not legal or benefits advice. RecordingLaw.com is not affiliated with, endorsed by, or sponsored by the Social Security Administration. Figures come from SSA's Federal Register notices for 2024, 2025 and 2026 and from Title 20 of the Code of Federal Regulations; for an official figure, rely on SSA's notices to you or your my Social Security account.