DID Best Practice Guidelines

An authorized provider conducting a determination of intellectual disability (DID), or endorsing a previous DID, must use the DID Best Practice Guidelines (PDF) as required by 26 Texas Administrative Code (TAC) Chapter 304, Diagnostic Assessment.


FAQ Acronyms

  • ABAS — Adaptive Behavior Assessment System
  • ABL — Adaptive behavior level
  • AP — Authorized provider
  • ASD — Autism spectrum disorder
  • BPG — Best Practice Guidelines
  • CAP — Certified authorized provider
  • CARE — Client Assignment and Registration
  • CFC — Community First Choice
  • CLASS — Community Living Assistance and Support Services
  • CFR — Code of Federal Regulations
  • DID — Determination of intellectual disability
  • DBMD — Deaf Blind with Multiple Disabilities
  • DSM — Diagnostic and Statistical Manual of Mental Disorders
  • GR — General Revenue
  • HCS — Home and Community-based Services Waiver Program
  • HHS — Health and Human Services
  • ICD — International Statistical Classification of Diseases and Related Health Problems
  • ICF/IID — Intermediate care facility for individuals with an intellectual disability and related conditions
  • ID — Intellectual disability
  • IDD — Intellectual and developmental disability
  • ID/RC — Intellectual Disability and Related Conditions Assessment
  • IQ — Intelligence quotient
  • LAR — Legally authorized representative
  • LIDDA — Local intellectual and developmental disability authority
  • LOC — Level of care
  • NF — Nursing facility
  • PASRR — Preadmission Screening and Resident Review
  • RC — Related condition
  • RCESI — Related Condition Eligibility Screening Instrument
  • TAC — Texas Administrative Code
  • TxHmL — Texas Home Living
  • WAIS — Wechsler Adult Intelligence Scale
  • WISC — Wechsler Intelligence Scale for Children
  • VABS — Vineland Adaptive Behavior Scales

DID General Guidelines

If I diagnose a client with ID per DSM-5 standards at age 17 and they don’t currently qualify for services, can they qualify for services in the future if the IQ and adaptive levels meet the standards?
If, upon initial testing, an individual’s IQ score does not meet or fall below the maximum allowed IQ score to be eligible, but does so in subsequent testing, the DID report should describe the previous test results and provide an explanation or justification why current results are considered valid and thus an accurate reflection of the individual’s level of functioning.

Which adaptive behavior tests are accepted?
There are many assessment tools available. The measure that is chosen should consider the individual’s unique abilities and situation. Tests of adaptive functioning include but are not limited to current versions of the Vineland Adaptive Behavior Scales, Adaptive Behavior Assessment System, Inventory for Client and Agency Planning, and Scales of Independent Behavior. These measures satisfy the professional standards for validity and reliability required for their use with persons who have ID (IDD).

Use of Brief Assessment Instruments and Tests

Is the Leiter International Performance Scale, a nonverbal test for kids who are very young and nonverbal, still acceptable test?
Yes, the Leiter may be used if clinically appropriate.

When would a brief IQ test be used?
Use of brief tests of intelligence is discouraged to establish an individual’s initial eligibility for IDD programs. However, in limited situations, exceptions may be warranted. For example, if an individual has a well-established, documented testing history based on broad-based batteries and brief test results are consistent with this testing history, then a brief measure may be adequate for eligibility purposes. Another example may be when an individual does not have adequate attention and concentration to tolerate a more comprehensive measure and their adaptive functioning and history are consistent with intellectual disability.

Is the Slosson Intelligence Test still acceptable for use with individuals who are unable to take a more comprehensive assessment such as the WAIS or WISC? It is the only test that we have found so far that gives IQ scores within the lower severe and profound IQ ranges and measures both verbal and non-verbal abilities. 
Comprehensive standardized cognitive assessment tools are recommended when establishing initial eligibility for IDD programs and services. There are certain limited situations in which a brief test, including the Slosson, may be warranted. APs must explain the rationale for this choice and justify its use in the DID report.

When a Standardized Intellectual Assessment Cannot be Successfully Administered

Is a CAP allowed to exercise clinical judgment in the selection of appropriate adaptive instruments when conducting DID assessments and the need for an “estimated” IQ occurs? For instance, we find the ABAS-3 to be a highly useful instrument that yields rich information regarding the various domains of an individual’s adaptive functioning. It appears to us that it would be an acceptable instrument to provide an “estimated” IQ.
If an individual’s ability to comprehend oral instruction or visual demonstration is not adequate for a formal appraisal of general intellectual functioning, the use of the Adaptive Behavior Composite provided by the most current version of the Vineland Adaptive Behavior Scales may serve as an estimate of the individual’s intellectual functioning when accompanied by clinical justification explained in the DID report. However, not all measures of adaptive behavior (e.g., ICAP, ABAS, Scales of Independent Behavior) are appropriate for establishing an IQ score equivalent.

Do current DIDs with a diagnosis of Unspecified ID require a VABS-II be completed to give an estimated IQ score instead of using 19 as done previously?
If a standardized intellectual assessment cannot be successfully administered, an AP shall provide an estimated IQ score using the Adaptive Behavior Composite provided by the most current version of the Vineland Adaptive Behavior Scales.

Establishing the Origination of ID During the Developmental Period

Can evidence of onset be based on verbal feedback provided by family if no actual documentation is available (especially when assisting older individuals whose records might no longer be available)? Can a family member’s information be accepted for an older person if there was no testing or verification of the age of onset?
The most common method for establishing age of onset of ID is to rely upon reports of previous assessments. When records are no longer available or the individual may not have been in a traditional school setting (e.g., homeschool, outside of the United States), alternative methods of collecting information may be needed to gather historical information. An AP may use reports by other people, including the individual’s family and friends who know their history well. The DID report should provide specific examples as evidence (e.g., developmental delays, functional skills classes, inconsistent work history). The AP is reminded to rule out other possible causes of current functioning (e.g., neurological insult).

Should "provisional" IDD be used if the only source of developmental history is the client themselves?
A DID is used to determine eligibility and HHSC would be unable to accept a DID report with findings that are inconclusive or a provisional is given.

An AP must make every effort to obtain as much supporting evidence as possible and include in the DID report a detailed description of the information and references used to make a determination. Absent any record, an AP may use collateral information from reliable historian(s). The AP must use sound clinical judgment when deciding whether this is reliable information that can be used to support diagnostic conclusions/

Endorsement of a Previous Assessment

If a client’s IQ is in the normal range and there is no question of ID, is it okay to endorse a brief IQ test?
If an individual’s IQ is clearly in the average range and their testing history consistently demonstrates this, then validating a brief cognitive measure or endorsing a previous assessment report that used a brief cognitive measure may be sufficient depending on the age of the individual, how old the testing is, and whether they have experienced any mental or physical health changes since then.

Is a non-video telephone interview acceptable for endorsement if face-to-face interview cannot occur?
When an AP endorses a previous assessment, they are accepting the assessment and findings of a previous DID or diagnostic report without changes or additions. When conducting an endorsement, it is required that the AP complete a clinical interview and behavioral observations with the individual and, as needed, interview the LAR and others familiar with the individual. This aids in determining whether the previous results are currently valid. Audiovisual technology may be used if this is the individual’s preference and there are factors impeding their ability to meet in person; however, behavioral observations of the individual that corroborate the verbal interview must occur to confirm the data being considered for endorsement.

To clarify, testing is required for all individuals under the age of 22 for all programs across the board and not just CFC non-waiver, correct?

A DID may, but is not required, to be completed if the age of the person at their most recent testing was under 22 years and the testing was completed more than five years ago for HCS, TxHmL, CFC, and ICF/IID. The necessity of endorsing a previous DID report or conducting a new DID assessment is based on the AP’s clinical judgment.

When deciding whether another DID assessment or endorsement is needed, the AP should consider the individual’s age, developmental stage, diagnosis, level of functioning, mental health, changes in health or neurological status, environmental factors, and other individual and contextual variables. The comprehensiveness, overall quality, and validity of previous testing should also be considerations. For example, if a waiver slot has been released for a 9-year-old and the most recent DID on record is from when they were 3 years old, conducting a new DID to obtain updated information is likely needed. As another example, if a waiver slot has been released for a 35-year-old and the most recent DID on record is from when they were 18 years old, a new DID may or may not need to be conducted depending on their current functioning and other contextual variables compared to the last time testing was conducted.

Can a state hospital assist a LIDDA in completing a DID?
An AP employed by or contracted with a LIDDA may endorse a diagnostic assessment report from a qualified AP, including those employed by or contracted with a State Hospital, so long as this report includes all elements of a DID report required by 26 TAC §304.401 and §304.402 and the AP endorses this report per 26 TAC §304.403.


Does an individual transitioning from a NF have a different IQ requirement when enrolling in Medicaid Waivers such as HCS? I recall years ago that some information at that level had been discussed during a PASRR training.
An individual who enrolls in HCS by way of diverting or transitioning from a Nursing Facility (NF) must meet ICF/IID LOC I or LOC VIII criteria. LOC VIII does not have an IQ requirement but does have diagnostic and ABL requirements. For any other individual who is attempting to enroll into HCS, eligibility must be based on LOC I criteria, which includes an IQ requirement.

If an ICF/IID provider has accepted individuals in to their facilities, do they have to arrange for the individuals to see us as the LIDDA before we can authorize the ID/RC?
Yes. Per 26 TAC §261.244 (a) Except as provided in subsection (b) of this section, only a LIDDA may request enrollment of an applicant by HHSC. (b) A program provider may request enrollment of an applicant by HHSC in accordance with subsection (k) of this section if the applicant: (1) has received ICF/MR services from a non-state operated facility during the 180 days before the enrollment request; and (2) is not moving from or seeking admission to a state school or state center.

The DSM-IV diagnosis of Asperger’s assumes a higher IQ. If eligibility under LOC I is limited to a diagnosis of an RC with an IQ of 75 or less, would a person with Asperger’s be ineligible for services?
If a person is diagnosed with Asperger’s disorder based on ICD-10 F84.5 and currently meets DSM diagnostic criteria for ASD, they may be eligible if they meet the IQ and ABL criteria as required per LOC I or LOC VIII. In this example, if the person’s IQ score is over 75, they would not meet LOC I criteria.

However, if the same person has an ABL of II, III, or IV, they may meet LOC VIII criteria. Also, they may be eligible for GR funded services as a member of the LIDDA priority population regardless of IQ and ABL scores.

If an individual has been diagnosed with autism with an IQ of 85 but has an ABL of II, will they meet the criteria for LOC VIII?
Correct. A person meets LOC VIII criteria if they have an approved related condition diagnosed by a physician that manifested before the age of 22 years, including ASD, and have an ABL of II, III, or IV regardless of IQ score.

Would you explain LOC VIII and how a person does not need to have a diagnosis of ID to be eligible for services? Since LOC VIII requires a physician’s diagnosis, does the diagnosis or physician’s statement stand alone, without the AP needing to follow up with testing?
LOC VIII is based on the person having a primary diagnosis of an approved related condition diagnosed by a licensed physician that substantially impacts their functioning and manifested before the age of 22 years. Although IQ is not part of the determination of LOC VIII, a DID assessment or endorsement must be conducted in accordance with 26 TAC Chapter 304, Subchapter D to determine eligibility for some IDD waiver and non-waiver programs.

Eligibility for GR Services

If someone is coming in for a GR evaluation, should I be listing whether or not they are eligible for Medicaid Waiver programs?
APs offer recommendations responsive to the identified purpose of the evaluation. In the example given, we assume the person has not received an offer of waiver services and is not a member of an HCS waiver program target group. If this is the case, addressing an individual’s eligibility for a Medicaid program in advance of an offer to enroll would be premature. However, if the person is likely a part of this target group, the AP is encouraged to refer them to the interest list.

Is the RCESI required for eligibility for GR services?
No, the RCESI is not required for GR services. The presence of a related condition is only applicable to Medicaid programs.

Eligibility for Services Based on ASD

What exactly is meant by structured observation for ASD diagnosis?
Due to the complexity of ASD, this diagnosis should be based on multiple sources of information and not simply a checklist of criteria. When evaluating for ASD, a multimodal and multisource assessment approach is necessary. Assessment batteries should include standardized measures of observation, performance, and informant and self-reports. Areas to assess should include cognition, executive functioning, social communication and responsiveness, expressive and receptive language, sensory functioning, and emotional and behavioral functioning. If possible, multiple observations of the individual in both the testing and natural environments are ideal. Parsing out core symptoms from other conditions is important to ensure an accurate diagnosis is made, which ultimately influences the individual’s treatment. APs are encouraged to rule-out other conditions, evaluate for comorbid conditions, and search for underlying etiology (e.g., genetic syndromes, environmental opportunities).

What are best practices for ASD determination? ASD evidence + IQ possibly above 69, but ABL at least Level 1?
An individual diagnosed with ASD based on DSM criteria may be determined eligible for GR-funded services without regard to the IQ score or ABL. In contrast to Medicaid program eligibility, eligibility for GR services based on an individual’s having ASD does not require the individual to have a particular IQ score or ABL. For certain IDD waiver and non-waiver program eligibility, a person with ASD must meet LOC I or LOC VIII criteria.

If ASD is used as the RC for eligibility under LOC VIII, must the ASD be diagnosed by a physician? Must every RC be diagnosed by a doctor?
Any time eligibility is based wholly, or in part, on an approved related condition, including ASD, a licensed physician must attest to this diagnosis as required by TAC 26 §261.238 and §261.239.

Eligibility for Services Based on an Approved Related Condition

What if there is a conflict between physician’s diagnosis and AP’s assessment?
The AP should not confirm that the person is eligible for services but may explain in the DID report that eligibility is conditional upon a physician’s confirmation of the qualifying diagnosis. The AP should indicate in the DID report that the person may be eligible for services if other eligibility criteria (i.e., IQ, ABL) are met.

An AP may assist in this process by providing the individual, family, and/or caregiver with the link to the HHSC Approved Diagnostic Codes for Persons with Related Conditions or with a hard copy of the document that they can then review with their physician. The AP should refrain from suggesting diagnoses.

Is it sufficient for a physician to give an attestation with just the name of the diagnosis but no code?
The physician’s attestation of the diagnostic name/description may be sufficient if the diagnosis is based on the most recent version of ICD and the LIDDA staff is able to locate the correct, corresponding ICD diagnostic code.

Does it matter if the medical documentation is old?
Old medical documentation may assist efforts to establish an age of onset. However, names and corresponding ICD codes used for determining eligibility must be up to date and, if a related condition, must be attested to by a licensed physician.

When determining eligibility for a related condition, will I need to use Form 8662 for any program?
Per Form 8662 instructions, the RCESI is used to determine programmatic eligibility for the ICF/IID program, ICF/IID waiver programs (HCS, TxHmL, CLASS, and DBMD), and CFC non-waiver services, when the applicant does not have a diagnosis of ID at the time of application. This form is not used to determine eligibility for GR-funded services.

Who would complete Form 8662, psychologist or LIDDA?
A LIDDA may delegate this task to whomever the LIDDA deems appropriate, including but not limited to an AP or service coordinator.

Does a medical diagnosis for a NF resident need to be done by a physician instead of sending the consumer for testing with a psychologist who is going to defer to the physician anyway?
The diagnosis of an approved related condition must be made by a licensed physician. A DID assessment or endorsement must be conducted in accordance with 26 TAC Chapter 304, Subchapter D to determine eligibility for IDD waiver and non-waiver programs. Therefore, an AP would still need to evaluate this individual.

DID Report Elements

I had a client come in who was clearly born male, but identifies as a female. What gender do I put in the system?
In the TMHP and CARE systems, the only available options are Male, Female, and Other. When an individual applies for Medicaid, the only available options to designate gender are Male and Female. To avoid a possible disruption in Medicaid services, it is recommended to enter in the TMHP and CARE systems the name and gender identification that is consistent with the individual’s government records and legal documents (e.g., official government ID, Medicaid application).

Because the ID/RC and DID report must match, it is recommended that the AP document both the individual’s assigned sex at birth as well as their gender identity in the DID report.

If an AP identifies an RC but does not yet have the physician’s attestation and cannot obtain it within the 30 days by which the DID report must be completed, should the AP conclude the person is ineligible or state the person is eligible, pending the attestation?
The AP should not confirm that the person is eligible for services but may explain in the DID report that eligibility is conditional upon a physician’s confirmation of the qualifying diagnosis. The AP should indicate in the DID report that the person may be eligible for services if other eligibility criteria (i.e., IQ, ABL) are met.

An AP may assist in this process by providing the individual, family, and/or caregiver with the link to the HHSC Approved Diagnostic Codes for Persons with Related Conditions or with a hard copy of the document that they can then review with their physician. The AP should refrain from suggesting diagnoses.


What is a DID "update?” That term is used here when we are required to do an update for enrollment in HCS or TxHmL.
A DID update is an unofficial term sometimes used to refer to a re-evaluation, either through conducting a new DID assessment or endorsing a previous DID report. The term does not appear in rule, statute, or HHSC handbooks.

How do we stay informed on the most up to date information regarding the use of technology and other items related to DIDs?
Subscribe to GovDelivery to receive important broadcasts from HHSC (https://service.govdelivery.com/accounts/TXHHSC/subscriber/new).

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About Related Conditions please see the:

Questions about the DID Best Practice Guidelines can be sent to didbpg@hhsc.state.tx.us.