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SSI vs. SSDI: What Is the Difference?

Helping disability claimants since 1996. Attorney Eitan Dagan has spent 30 years helping people through Social Security Disability claims.

SSDI pays disability benefits to people who worked and paid Social Security taxes, while SSI pays benefits to people with disabilities who have little income and few resources, no matter their work history.

Reviewed by Eitan Dagan, attorney, on October 27, 2026.

SSDI in plain words

  • Short for Social Security Disability Insurance.
  • You must have worked in jobs that paid Social Security taxes.
  • Your check is based on your past earnings.
  • There is usually a five-month waiting period before benefits start.
  • Back pay can reach up to 12 months before the month you apply.

SSI in plain words

  • Short for Supplemental Security Income.
  • For people with disabilities, people who are blind, or people 65 and older.
  • You must have limited income and resources.
  • Work history does not matter.
  • SSI cannot pay for months before you apply. The first possible month is the month after you apply.
  • In most states, people on SSI can also get Medicaid.

What both programs share

Both are run by the Social Security Administration. For adults, the medical rules for disability are generally the same. In general, your condition must keep you from doing substantial work for at least 12 months, or be expected to cause death. Both have the same appeal steps if you are denied: see Denied? How to appeal.

Not sure which one you qualify for?

Many people are not sure. In your free first talk, we review your work history and your situation and tell you which program, or both, may fit. In downstate New York, we can send a driver to pick up your paperwork.

No fee unless you win. You will not be charged for case expenses if we do not win your case.

Frequently asked questions

What is the main difference between SSI and SSDI?

SSDI is based on your work history and the Social Security taxes you paid. SSI is based on financial need: it is for people with disabilities, or people 65 and older, who have little income and few resources.

Can I get both SSI and SSDI?

Yes, some people can. For example, someone with a small SSDI check and very little income or resources may also qualify for SSI.

Are the medical rules the same?

For adults, the medical rules for disability are generally the same in both programs. Children who apply for SSI have a separate definition of disability.

Do I need a work history for SSI?

No. SSI does not depend on your work history.

Which one pays back pay?

Both can pay past-due benefits. SSDI can pay for up to 12 months before the month you apply, after a five-month waiting period. SSI does not pay for months before you apply. See Disability back pay.

How much does a Social Security Disability lawyer cost?

No fee unless you win. You will not be charged for case expenses if we do not win your case. If you win, the fee comes from your past-due benefits under the standard Social Security fee agreement, and the Social Security Administration sets and approves the fee. Under that agreement the fee is 25% of your past-due benefits, up to $9,200.

Contact Law Offices of Eitan Dagan, P.C.

Law Offices of Eitan Dagan, P.C.
Main office: 86-52 Woodhaven Blvd, Woodhaven, NY 11421
Melville office: 200 Broadhollow Rd, Suite 207, Melville, NY 11747
Phone: 516-310-9160
Email: daganadmin@edaganlaw.com
Hours: Monday to Friday, 9 AM to 5 PM
Se habla español.

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