In order to be eligible to receive SSI benefits, individuals must prove the following:
• They are 65+ years of age or blind or disabled.
and
• They legally reside in one of the 50 states, the District of Columbia, Northern Mariana Islands, or are the child of military parent(s) assigned to permanent duty outside of the US, or are a student (certain restrictions apply) temporarily abroad.
and
• They have income and resources within certain limits (see subsections).
and
• They have applied for the benefits.

An individual may be ineligible if he or she is a resident of a public institution from the first day of a month through the last day of the same month, fails to apply for all other benefits for which they may be eligible (including Social Security benefits), has an unsatisfied warrant or violates parole conditions, fails to give SSA permission to contact any financial institution for financial records, or is outside the US for 30 consecutive days (with some exclusions). Numerous restrictions have been placed on who is eligible for the benefit, which is considered a welfare benefit. However, unlike social security benefits (Title II), earned work credits are not a requirement for SSI.

If insured for disability and not currently receiving benefits, an applicant for SSI also applies for Social Security Disability Insurance Benefits (DIB), and the standard by which applicants are judged to be disabled is virtually the same for both SSI and DIB

The decision as to whether an individual is disabled is made by the various state Disability Determination Services (DDS), which contract with the federal government to make such determinations. Although the DDS's are state agencies, they follow federal rules. This arrangement arose from the inception of OASDI, when some key members of Congress considered the Social Security Disability program should be administered employing federalism, fearing expansion of the federal government.

Aged, Disabled, or Blind
In order to be eligible for SSI, a person must meet the definition of being aged, disabled, or blind.

Aged - Being deemed aged consists of attaining the age of 65 or older. The Social Security Administration, like the United States Government in general, follows English common law and considers a person to attain an age the day before their birthday.

Disabled - Being deemed disabled consists of meeting the general disability definition used by the Social Security Administration:

"Disability means inability to engage in any SGA [substantial gainful activity] by reason of any medically determinable physical or mental impairment which can be expected to result in death, or has lasted or can be expected to last for a continuous period of not less than 12 months."

"The 1967 amendments specified that workers shall be determined to be under a disability only if the physical or mental impairment or impairments are of such severity that the individual is not only unable to do his previous work but cannot, considering his age, education, and work experience, engage in any other kind of substantial gainful work which exists in the national economy. This is regardless of whether any of these are true:

• Such work exists in the immediate area in which the claimant lives.
• A specific job vacancy exists.
• The claimant would be hired if they applied for work.

"The statute also specifies that 'work which exists in the national economy means work which exists in significant numbers either in the region where such individuals lives or in several regions of the country.'"

Substantial gainful activity (SGA), for the year 2013, is the ability to earn $1040 gross income in a month's period for most disabled individuals, and $1740 for those whose disability includes blindness.

In addition, children under the age of 18 can be determined to be disabled for SSI purposes "if the individual has a medically determinable impairment or combination of impairments that causes marked or severe functional limitation(s), and can be expected to result in death, or has lasted or can be expected to last for a continuous period of not less than 12 months."

Blind - Being deemed blind consists of meeting the following definition:

"central visual acuity of 20/200 or less in the better eye with the use of a correcting lens. An eye which has a limitation in the field of vision such that the widest diameter of the visual field subtends an angle no greater than 20 degrees should also be considered as having a central visual acuity of 20/200 or less."

In addition, for SSI purposes, an individual is considered blind regardless of the period of time they are expected to be blind or if they are performing substantial gainful activity.

Income
One of the requirements to receive SSI is that the individual's income must be below certain limits. These limits may vary based on the state in which the individual lives, his/her living arrangement, the number of people living in the residence, and the type of income. The limit varies on all of these factors and is described below, in the section on benefit computation.

Resources
Another requirement for SSI is that the individual's resources are below a certain limit. This amount is $2,000 for a single individual and $3,000 for an individual and their spouse (whether the spouse is eligible for SSI or not), $4,000 for a child applicant with one parent living in the household, and $5,000 for a child applicant with two parents living in the household. However, conditional benefits may be paid if a substantial portion of the resources are considered non-liquid, resources that cannot be sold within 20 working days, if they agree to sell the resources at their current market value within a specified period and repay the money after the non-liquid property is sold.

However, not all actual resources are counted in calculating an individual's or couple's resources for SSI purposes.

The resource limits were originally set at $1500 for an individual and $2500 for couples in 1974,  and were not linked to inflation. In 1987 the limits were raised to $1800/$2700, in 1988 to $1900/$2850 and in 1989 to $2000/$3000. Under current law they will remain at present levels indefinitely.

Residency
SSI benefits are not paid solely to US citizens, but may also be paid to aliens legally residing in the United States.Conversely, citizens may find themselves ineligible because they do not currently reside within the United States; exceptions apply for children of military parent(s) who were born overseas, were disabled or became blind overseas, or first applied for benefits overseas and for students studying abroad who were eligible for SSI in the month prior to leaving the US, whose absence will be for less than 1 year, and who are studying to enhance their ability to perform substantial gainful activity, sponsored by an educational institution in the US, and would not be available to the individual in the US.Several restrictions apply to the eligibility of aliens however. These include being in a "qualified alien" category and meeting an exception condition.

There are seven categories of qualified aliens based on Department of Homeland Security (DHS) immigration statuses. This includes:
• those admitted as Lawfully admitted for permanent residence (LAPR)
• those granted conditional entry pursuant to section (a)(7) of the Immigration and Nationality Act (INA)
• those paroled into the US under section 212(d)(5) of the INA for a period of at least 1 year
• those who are refugees admitted to the US under section 207 of the INA
• those granted asylum under section 208 of the INA
• those whose deportation is being withheld under sections 243(h) or 241(b)(3) of the INA
• Cuban/Haitian entrants under section 501(e) of the Refugee Education Assistance Act of 1980.

There are 5 exception conditions. These include:
• having already been receiving SSI on 8/22/1996
• having 40 qualifying credits (using SSI as a supplement to Retirement or Disability Insurance Benefits) when in LAPR status
• being a veteran, active duty member of the U. S. military service, or being the spouse or dependant child of an individual who is
• having been lawfully residing in the US on 8/22/1996 and being blind and disabled (excluding aged individuals)