The short answer
Social Security Disability Insurance, SSDI, is an insurance program for people who have worked long enough and paid Social Security taxes, and it pays a monthly amount based on lifetime earnings. Supplemental Security Income, SSI, is a needs-based program for people with little income and few resources, with no work history required, and in 2026 the federal rate is $994 a month for an individual and $1,491 for a couple. Both use the same medical definition of disability. SSDI has a five-month waiting period and leads to Medicare after 24 months of benefits. SSI has no waiting period and in most states leads to Medicaid. SSDI has no resource limit, while SSI limits savings to $2,000 for an individual and $3,000 for a couple. A person can qualify for both, and the SSDI payment then reduces SSI. You can apply for both at once.
Side by side
Swipe sideways to see the whole table.
| Feature | SSDI | SSI |
|---|---|---|
| What it is | Insurance based on your work record | A needs-based payment |
| Work history | Required: enough credits, from you or sometimes a parent or spouse | None required |
| Income and savings | No limit on savings or other income, though earnings from work are tested | Income counted, and savings limited to $2,000 or $3,000 for a couple |
| Monthly amount | Based on lifetime earnings | Up to $994 federal in 2026, less countable income, plus any state supplement |
| Waiting period | Five full months before payments start | None |
| Health coverage | Medicare after 24 months of benefits | Medicaid in most states, with no waiting period |
| Back pay | Up to a year before the application, once approved | From the application date |
| Family benefits | Spouse and children may qualify on your record | None on your record |
| Marriage | Does not change your benefit | A spouse's income and resources can reduce it |
Both programs ask the same question about your health: whether a medical condition keeps you from substantial work and is expected to last at least a year or end in death. The financial tests differ, and that decides which program pays. A person with a long work history and modest savings usually fits SSDI, a person with little work history and almost no savings usually fits SSI, and many people in between fit both.
Who qualifies for SSDI
SSDI depends on credits, which you earn through work covered by Social Security. Most adults need about 40 credits, 20 of them in the last 10 years, with fewer for younger workers. The monthly amount comes from your average lifetime earnings, so a worker with a long and well-paid history gets more. There is no test on savings or on other income, such as a spouse's pay.
Work after the application matters. If you earn above the substantial gainful activity amount, $1,690 a month in 2026, you generally will not be found disabled, and once you are on SSDI, a trial work period of nine months lets you test a job without losing benefits. A month counts when earnings exceed $1,210 in 2026. Our guide to working on SSDI explains the rules, and our guide to how Social Security decides disability explains the decision.
Who qualifies for SSI
SSI is for people who have little income and few resources, whether or not they have worked. In 2026 a person's savings and other countable assets must be $2,000 or less, or $3,000 for a couple, and the federal benefit rate is $994 a month for an individual and $1,491 for a couple. Counting generally excludes the home you live in and one car. Income reduces the payment: Social Security ignores the first $20 of most income, and benefits from other programs reduce SSI dollar for dollar after that.
A spouse's income and resources count, which is why marriage can lower SSI, and for a child, the income of parents in the home can count. Our guide to SSI income and resource limits explains these rules, and our guide to working on SSI explains how earnings are treated.
Receiving both
Many people qualify for both programs, often because the SSDI amount is small. In that case the SSDI payment counts as income against SSI. After the $20 exclusion, SSI is reduced dollar for dollar, so the combined total is the SSI rate plus about $20, and the person gets Medicaid through SSI and Medicare after 24 months of SSDI.
Example (hypothetical): a short work history
A man who worked six years before a disabling illness is approved for SSDI of $900 a month. His savings are under $2,000. Social Security counts $880 of the $900 as income after the $20 exclusion, so his SSI payment is $994 minus $880, or $114, and his total is $1,014 a month. He has Medicaid through SSI and will receive Medicare after 24 months of SSDI benefits.
If you are owed back pay under both programs for the same months, the agency reduces the SSDI back pay by the SSI you would not have received had SSDI been paid on time. That rule, the windfall offset, can make the back pay smaller than expected.
A third route: benefits on a parent's record
A person whose disability began before age 22 may qualify for Social Security child's benefits on a parent's record, if the parent is retired, disabled or deceased. It is a Social Security benefit rather than SSI, it is not tested on the person's own savings, and it can lead to Medicare after 24 months. Marriage can end it, with exceptions, so check the rules first. Our guide to Social Security benefits for children explains who qualifies.
What changes over time
SSDI payments convert to retirement benefits at full retirement age, usually with no new application and the same amount. SSI continues as long as you meet the income and resource tests, and Social Security can require you to apply for any other benefit you may be owed, such as a retirement benefit, because other benefits reduce SSI. Children on SSI are reviewed at 18 under the adult rules, and because a parent's income is generally no longer counted, some young adults qualify who did not as children.
Both programs review cases from time to time. Keep your medical treatment up to date, answer any review forms promptly and report changes, since a missed form can stop payments.
Which to apply for
You do not have to choose. When you apply for disability benefits, Social Security looks at both programs and tells you which you qualify for. You can apply online, by phone at 1-800-772-1213 or at a local office, and a person who has worked recently and has low income and savings can often apply for both at once. If your application is denied, you have 60 days to appeal, and our guide to appealing a denied decision lists the steps.
Apply as soon as your condition stops you from working, because SSDI back pay is limited and SSI starts only from the application date. Gather medical records, a list of providers and your work history before you begin. Include the names and addresses of every doctor, clinic and hospital that has treated you, the dates of treatment and the medicines you take, because the agency requests records from them and a missing provider can slow the decision. Keep copies of everything you submit.
Questions about SSI and SSDI
Can I get SSI and SSDI at the same time?
Yes, if you meet the rules for both. The SSDI payment counts as income against SSI, so SSI is reduced dollar for dollar after a $20 exclusion. Many people receive both when SSDI is small.
Which program pays more, SSI or SSDI?
It depends on your earnings history. SSDI can pay more or less than the SSI rate, and a worker with a long, well-paid career usually receives more than the $994 federal SSI amount.
Can I apply if I am working part time?
Yes, but earnings above the substantial gainful activity amount, $1,690 a month in 2026, generally lead to a finding that you are not disabled. Report work on the application and ask about your options.
Does SSDI mean I will not get Medicaid?
No. SSDI leads to Medicare after 24 months, but you can qualify for Medicaid if your income and resources are low, and many people have both.
What decides your case
Social Security decides each application, and amounts and limits change each year. This is general information and not legal advice. A disability attorney or a legal aid office can help with an application or an appeal, and fees for representation are set by law.
Official sources
Before you apply
Check your earnings record for enough credits, count your savings against the $2,000 limit and gather medical records. Then estimate an SSDI amount with the SSDI calculator and compare it with the SSI rate.
