Regulation Basis Code

Definition

The Regulation Basis Code (RBC) is an administrative code recorded by Disability Determination Service (DDS) agencies in the Social Security Administration (SSA)-831 disability applicant file. It specifies the precise regulatory criterion — step of the SSA Sequential Determination Process, program (disability insurance (DI) or Supplemental Security Income (SSI)), and specific legal basis — for each allow or deny determination made by the DDS. It is the primary tool for parsing DDS decisions in SSA administrative data.

Key Ideas

• The RBC appears in the National Disability Determination Services System (NDDSS), which the DDS generates; the NDDSS then populates the SSA-831 file and related research datasets.
• Each RBC value maps to a specific combination of: (1) decision outcome (allow/deny), (2) step of the sequential process, and (3) the legal/medical/vocational criterion invoked.
• Wixon and Strand (2013) provide the canonical mapping of RBC values to sequential determination steps, separately for DI (Title II) disabled workers, SSI (Title XVI) adults, and SSI children.

How It Works

Data Source

The 831 file (Form SSA-831) is the transaction-level record of DDS determinations. Each claim generates a record; a person with multiple claims generates multiple records. The 831 file covers:

• DDS initial determinations
• DDS reconsiderations It does not cover field-office decisions (Substantial Gainful Activity (SGA) denials, financial eligibility), administrative law judge (ALJ) decisions, or higher-level appeals.

Key RBC Values (DI Disabled Workers)

Selected codes from Table 1 of Wixon and Strand (2013):

Code	Step	Decision	Basis
N1/N2	1	Deny	Engaging in SGA
F1/F2	2	Deny	Impairment not severe
E1–E4	2	Deny	Duration test failure
A1	3	Allow	Meets the Listings
B1	3	Allow	Equals the Listings
H1/H2	4	Deny	Capacity for past work
C1	5	Allow	Medical-vocational considerations
D1	5	Allow	Medical-vocational (arduous unskilled work)
J1/J2	5	Deny	Capacity for other work
Z1/Z2	5	Deny	Drug addiction/alcoholism material to disability
CE	—	Allow	Collateral estoppel (prior favorable determination)
K1/K2	—	Deny	Failure to follow prescribed treatment
L1/L2	—	Deny	Failure/refusal to submit to consultative exam
M3–M8	—	Deny	Insufficient evidence / does not want to continue

ER/PP suffix (met/not met): Indicates whether the Expedited Reinstatement (ER) or Provisional Period (PP) criteria were met — relevant for Ticket to Work clients attempting reentry.

Limitations for Research

• Step 1 (SGA and financial) denials are mostly made at SSA field offices, not DDS; the 831 file captures virtually none of them.
• The 831 file is transaction-based; duplicate claims per person must be handled.
• RBC values differ between the 831 file and the Disability Operational Data Store (DIODS), which uses a three-character prefix for Title XVI codes.
• ALJ-level outcomes require the Case Processing and Management System, not the 831/NDDSS.

Why It Matters

The RBC enables researchers to decompose aggregate allowance and denial trends by the specific regulatory criterion applied. Without it, broad program statistics (allowance rates, award counts) are uninterpretable — a rising allowance rate could reflect more Listings-based medical approvals, more vocational approvals, or fewer not-severe denials, each with different implications for program cost and beneficiary composition.

Related

• SSA Sequential Determination Process
• Social Security Administration
• Listing of Impairments
• Vocational Grid

Sources

• Wixon and Strand 2013 — Identifying SSA's Sequential Disability Determination Steps