Nexus Letter for PTSD: What It Must Say
The medical opinion connecting PTSD (9411, 9400, 9403, 9404, 9410, 9412, 9413, 9416, 9417, 9421, 9431, 9432, 9433, 9434, 9435, 9440) to your service is the piece of the file a rater weighs most heavily. This is what that letter has to contain — and a complete, real example you can read before writing a word.
What a nexus letter is
A nexus letter is a written medical opinion from a licensed clinician stating that a veteran’s condition is “at least as likely as not” (a 50 percent or greater probability) connected to their military service — or to a condition already service-connected. It is the bridge between a diagnosis and service connection: the VA has your diagnosis and your service records, and the nexus opinion is what ties them together with medical reasoning a rater can weigh.
What a PTSD nexus letter must contain
The diagnosis, by name and code
PTSD named as a current, documented diagnosis — the condition the VA rates under 38 CFR Part 4, DC 9411 / 9434 (9411, 9400, 9403, 9404, 9410, 9412, 9413, 9416, 9417, 9421, 9431, 9432, 9433, 9434, 9435, 9440). No diagnosis, no service connection: the opinion has to be about a condition that exists in your records.
The theory of connection
For most PTSD claims this is direct service connection under 38 C.F.R. § 3.303 — the letter connects the condition to an in-service event, injury, or exposure, and says so explicitly.
The magic words, used correctly
The opinion must be stated to the VA's own standard: "at least as likely as not (a 50 percent or greater probability)." Weaker hedges like "possibly" or "may be related" fail; the standard is a specific legal threshold, and letters that don't invoke it get discounted.
A rationale, not a conclusion
The most common fatal flaw is the conclusory letter — an opinion with no reasoning. A rater is instructed to weigh the rationale: what in the records supports the connection, what the medical literature says about the mechanism, and why known alternative causes don't displace it. For PTSD specifically: The picture on your WORST days, in specific scenes — how often the panic hits, what a week of sleep looks like, what it has cost at work and at home; a statement that minimizes gets the lower level.
A licensed clinician's signature and credentials
The letter is medical evidence only when a licensed clinician — opining within their specialty — reviews it, exercises independent judgment, and signs it with their credentials. VA Claim Commander drafts the letter from your records and your story; your clinician signs it. An unsigned draft is a draft.
Why nexus letters fail
- Conclusory: an opinion with no rationale. The rater is told to weigh reasoning, and a bare “it’s related” weighs nothing.
- Wrong standard: “may be related” or “possibly caused by” instead of “at least as likely as not.”
- Ignores the other causes: a strong letter names the recognized non-service risk factors and explains why they don’t displace the service connection.
- Outside the specialty: a clinician opining far from their field gets less weight than one whose practice covers the condition.
- Unsigned: a draft nobody signed is not medical evidence — it is homework.
Read a complete nexus letter — free, no account
4,348 words, 11 verified studies, the § 3.310 secondary framework — published in full so you can see the standard before you write a word.
Drafts are prepared for review and signature by a licensed clinician. Documentation quality is the promise — never a claim outcome.
Common questions
Do I need a nexus letter for a PTSD VA claim?
If service connection isn't already established for PTSD, a medical nexus opinion is usually the piece a rater weighs most heavily. It connects the diagnosis (9411, 9400, 9403, 9404, 9410, 9412, 9413, 9416, 9417, 9421, 9431, 9432, 9433, 9434, 9435, 9440) to your service — or to an already service-connected condition — using the "at least as likely as not" standard. Presumptive claims are the main exception.
What must a nexus letter for PTSD say?
Four things: the current diagnosis by name and diagnostic code; the connection theory (direct under 38 C.F.R. § 3.303, or secondary under § 3.310); the opinion stated to the "at least as likely as not (50 percent or greater probability)" standard; and a medical rationale grounded in your records and the medical literature — not a bare conclusion. It must be signed by a licensed clinician.
Who has to sign a nexus letter?
A licensed medical professional — a physician, or another clinician opining within their specialty. VA Claim Commander drafts the letter from your own records and story; a licensed clinician reviews, exercises independent judgment, and signs. An unsigned draft is not medical evidence.