A nexus letter is a signed medical opinion that links your current condition to your military service, or to a condition the VA has already service-connected. Below: what VA needs it to say, what makes one strong, a free fill-in template, and example outlines for a knee, back pain, and a secondary condition.
"Nexus" means connection. Most service-connection claims need three things: a current diagnosis, an in-service event, injury, or exposure, and a medical link between them (how a VA claim works). VA may get that link from its own C&P examiner. A nexus letter is your own provider's opinion on the same question, and it can carry the claim when the examiner's opinion is missing or negative.
You usually do not need one for a presumptive condition, where VA already assumes the link.
VA does not require certainty. Under 38 CFR 3.102, when the evidence for and against is in approximate balance, the reasonable doubt is resolved in the veteran's favor. Medical opinions express that balance with the phrase "at least as likely as not" (a 50 percent or greater probability). An opinion that says "possibly," "may be," or "could be related" is speculation and usually gets little weight.
The condition began in, or was caused by, service. Under 3.303(d) a condition first diagnosed after discharge can still be service-connected when the evidence shows it was incurred in service. The opinion ties your diagnosis to a specific in-service event.
The condition is "proximately due to or the result of" a service-connected condition (3.310(a)), or a service-connected condition made it worse (aggravation, 3.310(b)). For aggravation, VA needs medical evidence of the baseline severity before it worsened. See common secondary conditions →
Give this to your provider along with your records. Everything in [brackets] is for the provider to complete from the medical evidence.
[DATE] Re: Medical opinion for [VETERAN FULL NAME], [BRANCH], VA file no. [FILE NUMBER] To the Department of Veterans Affairs: I am [DOCTOR NAME], [CREDENTIALS], [SPECIALTY], licensed in [STATE], license no. [NUMBER]. I [have treated the veteran since DATE / examined the veteran on DATE]. Records reviewed: [LIST: service treatment records, VA and private treatment records, imaging or test results with dates, the veteran's statement, buddy statements]. Diagnosis: [CURRENT DIAGNOSIS, with the date and basis of diagnosis]. Opinion: It is my opinion that the veteran's [CURRENT CONDITION] is at least as likely as not (50 percent or greater probability) [caused by / aggravated beyond its natural progression by] [THE IN-SERVICE EVENT, INJURY, OR EXPOSURE / THE SERVICE-CONNECTED CONDITION]. Rationale: [THE DOCTOR'S MEDICAL REASONING: how the event or condition leads to this diagnosis, what in the records supports it, the timeline, and why other causes are less likely. Cite medical literature if relevant.] [SIGNATURE] [PRINTED NAME, CREDENTIALS] [CONTACT INFORMATION]
These outlines show how the template adapts to common claims. They are deliberately left blank where medical facts go: the facts and the reasoning have to come from your provider and your records. For a filled-in illustration using a fictional veteran, see VA claim evidence examples.
Diagnosis: [e.g., the knee diagnosis in your records, with imaging date] In-service event: [e.g., the injury, date, and where it appears in your service treatment records] Opinion: [knee diagnosis] is at least as likely as not caused by [in-service event]. Rationale points for the doctor to address: - what the service records show about the injury or repeated stress - [symptoms / treatment since service, with dates] (continuity) - why the current findings fit that history - why other causes are less likely [only if the doctor believes so]
Tip: The doctor writes the medical facts. Your job is to hand them the records and the timeline, not to supply the conclusion.
Diagnosis: [e.g., the lumbar spine diagnosis, not just "back pain"] In-service event: [e.g., the lifting injury, jump, or vehicle accident, with dates] Opinion: [back diagnosis] is at least as likely as not caused by [in-service event]. Rationale points for the doctor to address: - the service treatment record entries [dates] - [imaging results and dates] - [treatment and symptoms since service] - how the mechanism of injury fits the current findings
Tip: VA rates a diagnosis, not a symptom. "Back pain" alone is weak; make sure your records name the condition.
Service-connected condition: [e.g., your rated knee, back, PTSD, or diabetes] Claimed secondary: [current diagnosis] Opinion: [secondary condition] is at least as likely as not (a) caused by, OR (b) aggravated beyond its natural progression by [the service-connected condition or its treatment, such as a medication]. Rationale points for the doctor to address: - the mechanism, such as an altered gait, medication side effect, or sleep disruption - when the secondary began relative to the service-connected condition - for aggravation: the baseline severity before it worsened [dated records]
Tip: Ask the doctor to address both causation and aggravation. VA can grant either, and an opinion that covers only one gives the rater an easy reason to deny.
Ask your treating provider first (VA or private). A one-time C&P examiner evaluates you for VA, is not your treating provider, and generally will not write your nexus letter. Submit the signed letter with your claim on VA.gov, or with a Supplemental Claim if you were denied for lack of a nexus. A free accredited VSO can review it before you file.
Related: knee secondaries · back secondaries · PTSD secondaries · how to file a VA claim
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