If you're applying for Social Security Disability benefits, it can feel like you're learning an entirely new language.
SSDI, SSI, SGA, RFC, ALJ, DLI—what does all of it mean?
Understanding these terms can make it much easier to follow your Social Security Disability claim, read letters from the Social Security Administration (SSA), communicate with your doctors or representative, and understand what is happening during an appeal.
This glossary explains 50 important Social Security Disability terms in plain English.
Quick Answer
Social Security Disability terminology includes words and abbreviations used by the Social Security Administration to determine whether someone qualifies for disability benefits.
Some of the most important terms to understand include:
- SSDI — Social Security Disability Insurance
- SSI — Supplemental Security Income
- SGA — Substantial Gainful Activity
- RFC — Residual Functional Capacity
- ALJ — Administrative Law Judge
- DLI — Date Last Insured
- DDS — Disability Determination Services
- MDI — Medically Determinable Impairment
Knowing these terms can help you better understand your disability claim from the initial application through appeals.
50 Social Security Disability Terms and Definitions
1. Social Security Administration (SSA)
The Social Security Administration, commonly called SSA, is the federal agency that administers Social Security programs, including Social Security Disability Insurance and Supplemental Security Income.
2. Social Security Disability Insurance (SSDI)
SSDI is a federal disability program for people who meet Social Security's definition of disability and have generally earned enough work credits through employment covered by Social Security.
Eligibility isn't based simply on having a low income.
3. Supplemental Security Income (SSI)
SSI provides monthly payments to qualifying people with limited income and resources who are disabled, blind, or age 65 or older.
Unlike SSDI, eligibility for SSI generally does not depend on having a sufficient work history.
4. Disability
For adults, Social Security generally considers someone disabled when a medically determinable physical or mental impairment prevents them from engaging in substantial gainful activity and:
- The condition has lasted at least 12 months,
- Is expected to last at least 12 months, or
- Is expected to result in death.
SSA's definition of disability is different from definitions used by some employers, insurance companies, VA programs, and other agencies.
5. Substantial Gainful Activity (SGA)
SGA stands for Substantial Gainful Activity.
SSA uses earnings guidelines when evaluating whether someone's work activity may be considered substantial and gainful.
The dollar amount can change each year, so applicants should check SSA's current SGA limits.
6. Work Credits
Work credits are credits earned through work and payment of Social Security taxes.
The number of credits generally needed for SSDI depends partly on your age when disability begins.
7. Date Last Insured (DLI)
Your Date Last Insured is an important date in an SSDI claim.
Generally, you must establish that your disability began on or before your Date Last Insured to qualify for SSDI on that work record.
8. Alleged Onset Date (AOD)
The Alleged Onset Date is the date you report that your disability began preventing you from working at the level required by SSA.
SSA may ultimately establish a different onset date.
9. Established Onset Date (EOD)
The Established Onset Date is the disability onset date SSA ultimately accepts when it finds you disabled.
It may be the same as—or different from—the date you originally alleged.
10. Medically Determinable Impairment (MDI)
A Medically Determinable Impairment is a physical or mental impairment established by acceptable medical evidence.
Symptoms alone generally aren't enough. SSA needs objective medical evidence from an acceptable medical source to establish the existence of an impairment.
11. Residual Functional Capacity (RFC)
Your Residual Functional Capacity describes the most you can still do in a work setting despite limitations caused by your medically determinable impairments.
SSA may evaluate abilities such as:
- Sitting
- Standing
- Walking
- Lifting
- Carrying
- Reaching
- Handling objects
- Following instructions
- Concentrating
- Interacting with others
RFC can play a major role in disability decisions.
12. Medical Evidence
Medical evidence can include records used to evaluate your conditions and limitations, such as:
- Treatment notes
- Medical test results
- Imaging
- Laboratory results
- Diagnoses
- Examination findings
- Medical opinions
Medical evidence is a central part of a Social Security Disability claim.
13. Objective Medical Evidence
Objective medical evidence includes medical signs and laboratory findings that can help establish a medically determinable impairment.
Examples may include examination findings, imaging results, laboratory testing, or other medically acceptable diagnostic evidence.
14. Acceptable Medical Source (AMS)
An Acceptable Medical Source is a medical professional SSA recognizes for certain evidentiary purposes, including establishing the existence of a medically determinable impairment.
The types of professionals that qualify depend on SSA regulations.
15. Consultative Examination (CE)
A Consultative Examination is a medical or psychological examination SSA may arrange when the existing evidence isn't sufficient to make a determination.
SSA generally pays for the examination.
A CE does not automatically mean your claim will be approved or denied.
16. Disability Determination Services (DDS)
Disability Determination Services are state agencies that make many initial medical disability determinations for SSA.
DDS may review medical records, request additional evidence, and arrange consultative examinations.
17. Blue Book
The Blue Book is the informal name commonly used for SSA's Listing of Impairments.
It describes medical criteria SSA uses at one stage of the disability evaluation process.
You do not necessarily have to meet a listing to ultimately be found disabled.
18. Listing of Impairments
The Listing of Impairments contains medical criteria for impairments SSA considers severe enough to satisfy the medical requirements for disability when all applicable requirements are met.
Listings are organized by body system.
19. Five-Step Sequential Evaluation Process
SSA generally uses a five-step sequential evaluation process when determining adult disability.
The process asks questions about:
- Current work activity
- Severity of impairments
- Whether an impairment meets or medically equals a listing
- Ability to perform past relevant work
- Ability to adjust to other work
20. Severe Impairment
A severe impairment is an impairment—or combination of impairments—that significantly limits a person's ability to perform basic work activities.
This concept is evaluated during the sequential disability process.
21. Non-Severe Impairment
A non-severe impairment is generally one that does not significantly limit the ability to perform basic work activities.
SSA considers the combined effects of medically determinable impairments when required by its rules.
22. Medical Equivalence
An impairment may medically equal a listing when it doesn't meet the listing exactly but the medical findings are at least equal in severity and duration to the criteria of a listed impairment under SSA's rules.
23. Past Relevant Work (PRW)
Past Relevant Work refers to certain work you performed in the past that SSA considers when evaluating whether you can return to previous work.
Specific rules determine which prior jobs qualify as past relevant work.
24. Vocational Expert (VE)
A Vocational Expert is a specialist who may testify during a Social Security Disability hearing about jobs and vocational issues.
The ALJ may ask the VE hypothetical questions involving different work-related limitations.
25. Medical Expert (ME)
A Medical Expert is a medical professional who may provide expert testimony or medical opinions in connection with a disability claim.
Medical experts do not decide whether the claimant is disabled.
26. Administrative Law Judge (ALJ)
An Administrative Law Judge conducts Social Security hearings and issues decisions on appealed claims.
The hearing gives claimants an opportunity to present their case after earlier levels of review.
27. Reconsideration
Reconsideration is an appeal level available after an initial disability claim is denied in most states.
A different reviewer generally evaluates the claim and any additional evidence.
28. Disability Hearing
A disability hearing before an ALJ is an opportunity to present your case after the applicable earlier appeal stages.
Depending on the circumstances, hearings may occur in person, by video, or by telephone, and SSA may offer other appearance options.
29. Appeals Council
The Appeals Council reviews certain requests involving ALJ decisions or dismissals.
It may deny the request for review, grant review and issue an action or decision, or send a case back for additional proceedings.
30. Remand
A remand occurs when a case is sent back to a previous level for additional action.
For example, the Appeals Council or a federal court may send a case back for another hearing or further consideration.
31. Federal Court Review
After completing the applicable administrative appeals process, a claimant may be able to file a civil action in federal district court challenging SSA's final decision.
Strict deadlines apply.
32. Denial Notice
A denial notice is SSA's written explanation that a claim or appeal was denied.
It may explain the decision and provide information about appeal rights and deadlines.
Read the entire notice carefully.
33. Appeal
An appeal is a request asking SSA to review a decision you disagree with.
Appeal deadlines are important. Waiting too long can affect your ability to continue the claim through the normal appeals process.
34. Protective Filing Date
A protective filing date can preserve an earlier application date in certain circumstances when a person contacts SSA and indicates an intent to file for benefits.
This can potentially affect eligibility or payments depending on the program and circumstances.
35. Application Date
The application date is the date associated with filing your claim for benefits.
Application dates can be particularly important because SSDI and SSI have different rules governing potential payments.
36. Back Pay
Back pay is a commonly used term for past-due disability benefits owed for eligible months before ongoing payments begin.
The amount and period depend on factors such as the program, relevant dates, and SSA's payment rules.
37. Five-Month Waiting Period
SSDI generally has a five-full-calendar-month waiting period after the established onset of disability before entitlement to disability benefits can begin, subject to exceptions under SSA rules.
SSI does not use the same five-month SSDI waiting period.
38. Retroactive Benefits
Retroactive benefits generally refer to SSDI benefits that may be payable for eligible months before the application date.
SSDI may allow limited retroactivity subject to SSA's rules.
SSI has different payment rules and generally does not pay benefits for months before the application filing date.
39. Continuing Disability Review (CDR)
A Continuing Disability Review is a review SSA conducts after approval to determine whether a beneficiary continues to meet disability requirements.
Not every beneficiary is reviewed on the same schedule.
40. Medical Improvement
Medical improvement generally refers to a decrease in the medical severity of an impairment based on changes in symptoms, signs, or laboratory findings.
It can be important during continuing disability reviews.
41. Trial Work Period (TWP)
The Trial Work Period is an SSDI work incentive that can allow eligible beneficiaries to test their ability to work while maintaining disability benefits during qualifying trial work months, subject to SSA's rules.
The applicable earnings amount can change over time.
42. Extended Period of Eligibility (EPE)
The Extended Period of Eligibility is another SSDI work incentive that follows the Trial Work Period and can affect whether SSDI benefits are payable while a beneficiary works.
Specific rules and earnings thresholds apply.
43. Ticket to Work
Ticket to Work is a voluntary Social Security program designed to help eligible disability beneficiaries obtain employment services, vocational rehabilitation, or other employment support.
44. Compassionate Allowances (CAL)
Compassionate Allowances identify certain diseases and medical conditions that, by definition, meet Social Security's standards for disability.
The program allows SSA to identify qualifying claims more quickly.
45. Presumptive Disability
Presumptive Disability can allow certain SSI applicants with qualifying severe conditions to receive temporary payments while SSA completes its disability determination.
These payments are available only in certain circumstances.
46. Representative Payee
A Representative Payee is a person or organization SSA appoints to receive and manage Social Security or SSI benefits for someone who cannot adequately manage their own benefits.
The money must be used for the beneficiary's needs.
47. Authorized Representative
An Authorized Representative is someone a claimant appoints to assist with a Social Security matter.
Depending on the circumstances, this may be an attorney or a qualified non-attorney representative.
48. Function Report
A Function Report is a form SSA may use to gather information about how a person's medical conditions affect everyday activities and functioning.
Questions may address:
- Personal care
- Cooking
- Cleaning
- Shopping
- Driving
- Walking
- Lifting
- Concentration
- Social activities
- Ability to complete tasks
The answers can become part of the disability record.
49. Work History Report
A Work History Report provides SSA with detailed information about jobs you've performed.
It may ask about duties such as:
- How much you lifted
- How long you stood
- How long you sat
- How much you walked
- Whether you supervised others
- Equipment or tools you used
- Skills required for the job
Accurate descriptions are important because SSA may use this information when evaluating your ability to perform past work.
50. Disability Decision
A disability decision is SSA's determination regarding whether you meet its disability requirements at a particular stage of your claim.
Depending on the stage, you may receive an approval, denial, dismissal, or another type of action.
If you disagree with a decision, carefully review the notice for your appeal rights and deadline.
SSDI vs. SSI: What's the Difference?
Although people often use "Social Security Disability" to describe both programs, SSDI and SSI are different.
| SSDI | SSI |
|---|---|
| Based largely on insured status from covered work | Needs-based program |
| Requires sufficient work coverage in most cases | Does not require a qualifying work history |
| Has an SSDI waiting-period rule | No SSDI five-month waiting period |
| Can eventually provide Medicare eligibility | Generally associated with Medicaid eligibility, depending on state rules |
| Income/resource rules differ from SSI | Strict income and resource rules apply |
Some people can qualify for both SSDI and SSI at the same time, depending on their circumstances.
Which Social Security Disability Terms Are Most Important?
If you're just beginning the disability process, start by understanding these 10 terms:
- SSDI
- SSI
- SGA
- Work Credits
- Date Last Insured
- Medically Determinable Impairment
- RFC
- DDS
- ALJ
- Appeals Council
You'll encounter many of these repeatedly while applying for or appealing disability benefits.
Frequently Asked Questions About Social Security Disability Terms
What does SSDI stand for?
SSDI stands for Social Security Disability Insurance. It provides benefits to qualifying disabled workers who meet Social Security's disability requirements and applicable insured-status requirements.
What does SSI stand for?
SSI stands for Supplemental Security Income. It is a needs-based federal program for qualifying people who are disabled, blind, or age 65 or older and meet applicable financial requirements.
What does RFC mean in a disability claim?
RFC stands for Residual Functional Capacity. It describes the most work-related activity SSA determines you can still perform despite limitations resulting from medically determinable impairments.
What does ALJ mean?
ALJ stands for Administrative Law Judge. An ALJ conducts Social Security hearings and makes decisions on appealed claims.
What does SGA mean?
SGA stands for Substantial Gainful Activity. SSA uses SGA rules when evaluating work activity in disability cases. The applicable earnings amounts can change annually.
What does DLI mean?
DLI stands for Date Last Insured. In an SSDI claim, it can determine the period during which you generally need to establish that your disability began.
Can you get Social Security Disability without meeting a Blue Book listing?
Yes. Meeting or medically equaling a listing is one way to satisfy part of SSA's disability evaluation, but a claimant who doesn't meet a listing may still be found disabled later in the sequential evaluation based on RFC, vocational factors, and other applicable rules.
Key Takeaways
Social Security Disability terminology can be confusing when you're first applying for benefits.
You don't need to memorize every abbreviation at once.
Start with the terms that appear in your SSA notices and medical paperwork. As your claim moves through the process, understanding terms such as RFC, SGA, DLI, DDS, reconsideration, ALJ, and Appeals Council can make it much easier to understand what's happening with your case.
Bookmark this glossary and return whenever you encounter an unfamiliar Social Security Disability term.
Continue Learning About Social Security Disability
Consider reading these DisabilityTips.org guides next:
- How to Apply for Social Security Disability
- SSDI vs. SSI: What's the Difference?
- What Happens After You Apply for SSDI?
- What to Do If Your Disability Claim Is Denied
- How the Social Security Disability Appeals Process Works
- What Happens at an ALJ Disability Hearing?
- How SSA Determines If You Are Disabled
- What Is an RFC in a Social Security Disability Claim?
- What Medical Evidence Does Social Security Look For?
- How Does Social Security Disability Back Pay Work?
Disclaimer
The information provided on DisabilityTips.org is for general educational and informational purposes only. It is not legal, medical, financial, or professional advice and does not create an attorney-client relationship. Social Security rules, benefit amounts, earnings limits, and procedures can change. Always verify current requirements with the Social Security Administration or consult a qualified professional about your individual situation.
Last reviewed: August 11, 2026
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