SSI vs. SSDI – Understanding the Difference

Knowing the difference of SSI vs. SSDI is an important part of understanding social security payments. SSDI (or SSD), which is Social Security Disability, is available to workers who have accumulated a sufficient number of work credits to qualify for such payments. SSI, or Supplemental Security Income, is a set of benefits available to individuals who have not earned enough work credits to qualify for Social Security Disability, or perhaps who have never worked.

The two programs, SSI and SSDI, are entirely different programs of the U.S. government. The Social Security Administration manages both programs and oversees both, but there are considerable differences between the two. The medical requirements for both programs are essentially the same, but the programs’ similarities end there.

Understanding SSI

SSI is strictly need-based, and is awarded according to assets and income. General fund taxes are the source of SSI funding – not the Social Security trust fund, as many people think – and to qualify, an individual must have less than $2,000 in assets. For a couple, this line is at $3,000.

Most individuals who qualify for SSI can also receive food stamps. The amount of food stamps issued is largely based on the individual’s location, and the amount of consistent, monthly income they have. People who are disabled and meet the SSI income requirement can also apply for Medicaid coverage in their state of residence.


A large number of SSI recipients are either homeless or are considered “housing insecure,” which is a designation meaning that the person’s living situation is tentative. People who pay more than half of their monthly income on housing often fall into this category, and the government definition of “affordable housing” is housing that costs less than one-third of the income for a household. If people are not necessarily living on the street, but need to move often for economic reasons — every few months, for example — then they are housing insecure, and may stand a good chance of qualifying for SSI.

SSI is a program designed for older US residents. To qualify for SSI, you must be 65 or older. For this reason, the program often goes hand-in-hand with Medicaid and other care programs intended for older people approaching retirement.

By this same token, disabled senior citizens can qualify for SSI along with their Social Security benefits. One of the requirements for receiving SSI benefit is that you have applied for other cash benefits, including Social Security retirement benefits. Your monthly benefit amount does not decrease if you qualify for both SSI and Social Security, so many people are able to receive both sets of benefits. As you recall, SSI is not paid out of the Social Security fund, but out of the United States Treasury’s general fund.

Understanding SSDI

SSDI, Social Security Disability, is funded through payroll taxes. People who receive SSDI have paid into the Social Security trust fund in the form of FICA Social Security taxes, and are therefore considered to be “insured.” These individuals have worked for a certain number of years and have earned a minimum number of “work credits.”

How Do Work Credits Function?

As an employee, you can earn up to four work credits each year. The amount of work that equals one credit changes each year, so definitely check the Social Security Administration website for the latest figures.

In 2021, you earn one credit for each $1,470 you earn either in self-employment income or in wages. Once you have earned at least $5,880 in 2021, you have earned the four credits that you can earn in 2021.

You cannot earn more than four credits in a single year.

To qualify for SSDI benefits, you usually need 40 credits. 20 of those 40 credits need to have been earned within the past decade – that decade ending with the year during which you became disabled.

If you have not been old enough to work as many years as it would take to earn 40 credits, the calculation is done differently. In that case, there is a pro-rated scale for the amount of work credits you need to have earned.

When Am I Too Old for SSDI?

To receive SSDI, a person is younger than 65. After the age of 65, you receive your ordinary social security retirement. When you apply for SSDI, you are essentially asking for your retirement money early because you are incapable of working until you are 65.

If a SSDI recipient is disabled, the individual must receive SSDI for two years before becoming eligible for Medicare. Only adults over the age of 18 are eligible to receive an SSDI disability benefit, but the disabled person’s spouse and children, if they are listed as dependents, can receive auxiliary benefits, which are partial dependent benefits. As both of these benefits are paid out of the Social Security fund, qualification for one benefit negates eligibility for the other benefit.

You cannot receive SSDI and Social Security retirement benefits at the same time. SSDI is intended specifically for people who cannot work due to injury, but who are too young to receive retirement benefits.