38 CFR part 3 study guide for the claims agent exam

Sources checked October 5, 2026. Independent guide, not affiliated with VA. Not legal advice.

Part 3 of title 38, Code of Federal Regulations, is the VA's adjudication rulebook: how claims are decided, what counts as service connection, when benefits start, and what VA must do to help the claimant. OGC lists part 3 on the confirmed exam syllabus, and it is the largest substantive block on the test. This guide maps the sections that matter most.

How part 3 is organized

Part 3 runs from definitions (3.1) through pension, compensation, and DIC adjudication rules. For exam purposes, think of it in five clusters: evidence and process, service connection, effective dates, the duty to assist, and total or special ratings. Learn the clusters, then the key sections inside each.

Cluster 1: evidence and process

• 3.102, reasonable doubt. When the evidence for and against the claim is in approximate balance, doubt is resolved in the claimant's favor. This is the benefit-of-the-doubt rule, and it mirrors 38 U.S.C. 5107(b). It applies after VA has met its duty to assist, not as a shortcut around missing evidence.
• 3.103, procedural due process. Claimants have the right to notice of decisions, to a hearing, and to representation. This is the fairness backbone of the whole system.
• 3.104 and 3.105, finality and revision. Decisions become final, but 3.105(a) allows revision based on clear and unmistakable error (CUE), and 3.105(e) addresses difference of opinion. CUE is a high bar: the error must be undebatable and outcome-determinative, based on the record that existed at the time.
• 3.156, new and material evidence (legacy). In the legacy appeals system, a finally denied claim could be reopened with new and material evidence. Under the modernized review system (AMA), a supplemental claim instead requires "new and relevant" evidence (38 CFR 3.2501). The exam tests the difference: material versus relevant, legacy versus AMA.

Cluster 2: service connection (3.303 through 3.310)

This is the heart of part 3. Service connection comes in three main theories, plus presumptions:

• 3.303, principles of service connection. Paragraph (a) states the general rule; (b) covers chronicity and continuity of symptomatology, which lets a claimant bridge gaps in the record; (c) excludes congenital or developmental defects, refractive error of the eye, personality disorders, and mental deficiency as diseases or injuries; (d) addresses post-service initial diagnosis of a disease.
• 3.304, direct service connection. The disability resulted from disease or injury incurred in or aggravated by service. The classic three elements: a current disability, an in-service event or injury, and a nexus between them.
• 3.305, presumption of soundness. A veteran is presumed sound at entry except for defects noted at examination. The presumption can be rebutted only by clear and unmistakable evidence that the disability existed before service and was not aggravated by it.
• 3.306, aggravation of a preservice disability. If a disability noted at entry worsens during service, the worsening is presumed service-connected unless clear and unmistakable evidence shows the increase was due to the natural progress of the disease.
• 3.307 and 3.309, presumptive service connection. Certain chronic diseases (3.309(a)) manifesting to a compensable degree within one year of separation are presumed service-connected, as are certain tropical diseases (3.309(c)) within their stated periods. No in-service event needs to be shown for these.
• 3.310, secondary service connection. A disability proximately caused by, or aggravated by, a service-connected disability is itself service-connected. Note the aggravation prong: only the degree of aggravation beyond the natural baseline is compensable.

Cluster 3: effective dates (3.400)

Effective dates decide how much back pay a claimant gets, so the exam tests them hard. The general rule is that the effective date is the date of claim or the date entitlement arose, whichever is later, with exceptions:

• 3.400(b)(2)(i), direct service connection. If VA receives the claim within one year after separation, the effective date is the day after separation (or the date entitlement arose). Otherwise, it is the later of the date of claim or the date entitlement arose.
• 3.400(o), increases. The effective date of an increase is the earliest date the increase was factually ascertainable, but no earlier than the date of claim. The exam loves the trap of backdating an increase to when symptoms worsened without a claim on file.
• 3.400(p), liberalizing law. When a law or VA issue changes in the claimant's favor, the effective date rules shift; know that this exception exists and when it applies.

Also learn 3.400's interaction with intent-to-file and the one-year lookback, since filing strategy depends on it.

Cluster 4: the duty to assist (3.159)

Under 3.159 and 38 U.S.C. 5103A, VA must notify claimants of what evidence is needed, make reasonable efforts to obtain relevant records (federal and private), and provide a medical examination or opinion when one is necessary to decide the claim. For private records, reasonable efforts mean at least two requests to the custodian unless the first request shows a second would be futile (38 U.S.C. 5103A(b)(2)(B)). For federal records, VA must keep trying until it is reasonably certain the records do not exist or further efforts would be futile. The exam tests exactly that distinction.

Cluster 5: extraschedular and total ratings (3.321 through 3.350)

• 3.321(b), extraschedular ratings. When a disability presents an exceptional or unusual disability picture, with marked interference with employment or frequent hospitalization, VA may rate outside the schedule. This is the exception, not a second bite at the schedule.
• 3.340, total disability ratings. Total ratings may be schedular (100 percent) or based on individual unemployability.
• 3.343, total disability based on unemployability (TDIU). A veteran who cannot secure or follow a substantially gainful occupation due to service-connected disabilities may be rated totally disabled even without a 100 percent schedular rating, subject to the percentage thresholds in the regulation.
• 3.344, stabilization of disability evaluations. Ratings in effect for five years or more get special protection against reduction; know the examination and improvement requirements before VA may reduce.
• 3.350, special monthly compensation. Additional compensation for severe disabilities such as loss of use of extremities, housebound status, and aid and attendance.

How to study part 3

Read each key section in the eCFR, then close it and state the rule in one sentence. Then test yourself with questions: the sample questions and the free quiz both draw on part 3. Pay special attention to mirror-image traps: new and material versus new and relevant, private-record versus federal-record effort standards, and direct versus presumptive versus secondary service connection. For the full exam roadmap, see the study guide and the topic outline.