What Makes a Strong Nexus Letter for a VA Claim
A nexus letter is a clinician's signed opinion that your condition is at least as likely as not (50% or more) linked to service or to a service-connected condition. The strongest letters name the records reviewed, state the opinion plainly, and explain the medical reasoning.
Written by Staff Writer AI-assisted · YourVABenefits · Last updated October 2, 2026 · Who writes these
Last reviewed: October 2026. Based on VA's evidence guide, 38 CFR 3.102, 38 CFR 3.310 and VA's public DBQ page.
A nexus letter is a signed medical opinion that links your current condition to your service, or to a condition VA already service-connected. VA's evidence guide says that for this link it "usually" needs medical records or opinions from health care providers. YourVABenefits is independent and is not part of VA. You or your representative decide whether to send the letter to VA.
What is a nexus letter?
Most service-connection claims need three things: a current condition, an event, injury or illness in service, and a link between the two. VA's evidence guide lists all three. The "nexus" is the link. When your service records do not make the link plain, a clinician's written opinion can.
There is no VA form for a nexus letter. It is usually a one- or two-page letter on the clinician's letterhead, signed and dated.
What does "at least as likely as not" mean?
It means a 50 percent or greater chance. It is the phrase VA asks its own examiners to use. You can see it in Board of Veterans' Appeals decisions, such as this one, which asks the examiner whether a condition is "at least as likely as not (a 50 percent or greater probability)" related to service.
The standard is lower than medical certainty on purpose. Under 38 CFR 3.102, when the evidence for and against is about evenly balanced, VA must resolve the doubt in the veteran's favor. That same rule says doubt must be "within the range of probability," not "pure speculation or remote possibility." That is why words like "possibly" or "could be" carry little weight. They do not tell VA the odds.
What should a strong nexus letter include?
A strong letter answers the questions a VA rater will ask. It should include:
- Who the clinician is. Name, credentials, specialty, and how they know you (treating doctor, or reviewed your file).
- What they reviewed. Service treatment records, VA and private records, test results, and any statements, named specifically.
- The diagnosis. The current condition, with the findings that support it.
- The in-service event or the service-connected condition. Named with dates where the records show them.
- The opinion sentence. For example: "It is at least as likely as not (50 percent or greater probability) that the veteran's lumbar degenerative disc disease is related to the documented in-service injury of March 2009."
- The rationale. The medical reasons, in plain terms, that connect the facts to the opinion. A conclusion with no reasoning carries little weight, however qualified the writer.
- Signature and date.
Is it direct, secondary, or aggravation?
The opinion should name which kind of link it is making, because VA's rules treat them differently.
| Type of link | What the clinician addresses | VA rule |
|---|---|---|
| Direct | Service caused the condition, or it began in service | 38 CFR 3.303 |
| Secondary | A service-connected condition caused this new one | 38 CFR 3.310(a) |
| Aggravation by a service-connected condition | A service-connected condition made a non-service condition worse beyond its natural progress | 38 CFR 3.310(b) |
| Aggravation in service | A condition you had before service got worse during service | 38 CFR 3.306 |
A common secondary example is a service-connected knee that changes how you walk and leads to a back problem.
Who can write a nexus letter?
Any clinician who is qualified to give that kind of medical opinion. VA's rule at 38 CFR 3.159(a)(1) calls evidence "competent medical evidence" when it comes from a person qualified by education, training, or experience. That can be a private doctor or a VA clinician, and for mental health conditions, a psychologist. A private opinion counts as evidence just like a VA one. What matters most is the reasoning.
Does the clinician have to write it themselves?
The opinion must be the clinician's own. Some veterans bring their clinician a draft or an outline to save time. That is fine only if the clinician reads it, changes anything they do not agree with, and signs it as their own opinion. A clinician may also decide the condition is not related, or decline to write one. YourVABenefits' Super Intelligence (SI) platform reviews your records and can draft an outline your clinician may use, change, or reject.
What about Disability Benefits Questionnaires (DBQs)?
DBQs are VA forms that collect medical findings for a condition, such as range of motion or symptom frequency. VA's public DBQ page lets your own provider fill them out and submit them. But VA's "Medical Opinion" DBQ is on its list of DBQs not available for public use. So a DBQ can document diagnosis and severity, and a nexus letter carries the opinion on the link. VA says it does not pay for DBQs your provider completes, and you may still be scheduled for a VA exam.
When to submit a nexus letter
| Situation | Timing |
|---|---|
| First claim for the condition | Upload it with the claim on VA.gov |
| After a denial (Supplemental Claim) | Any time; within 1 year of the decision keeps your original effective date (38 CFR 3.2500) |
| Board Appeal, Evidence Submission docket | With the appeal or within 90 days after the Board receives it |
| Board Appeal, Hearing docket | At the hearing or within 90 days after it |
| Higher-Level Review | Not allowed; this lane takes no new evidence |
If VA denied a claim because the link was missing, a new nexus letter can be the new and relevant evidence a Supplemental Claim needs. Our free decision review tool helps you sort out which lane fits.
Frequently asked questions
What does "at least as likely as not" mean in a nexus letter? It means a 50 percent or greater chance that the condition is related to service. VA resolves an evenly balanced question in the veteran's favor under 38 CFR 3.102.
Does a nexus letter have to come from a specialist? No. Any clinician qualified to give the opinion can write one, and a private provider's opinion is valid evidence. The reasoning matters more than the title.
Is there a VA form for a nexus letter? No. It is a signed letter, usually on the clinician's letterhead. VA's Medical Opinion DBQ is not available for public use, so private opinions are written as letters.
Does VA pay for a nexus letter? VA's DBQ page says it does not pay or reimburse the cost of DBQs your own provider completes, and it lists no payment for private opinions. Some providers charge for their time, which is between you and them.
Can I write my own nexus letter? No. You can describe your symptoms and what happened in a personal statement, and others can write buddy statements. A medical opinion on cause must come from a qualified clinician.
What if my doctor will not say "at least as likely as not"? Respect their answer. You can ask whether something specific would change their view, such as a record they have not seen. You can also ask an accredited VSO, who can review your file for free; find one with our VSO finder.
YourVABenefits does not file claims or represent veterans, and this page is not medical or legal advice.
YourVABenefits is software you run on your own records. It is not part of the U.S. Department of Veterans Affairs and does not file claims. You file on VA.gov, or an accredited representative files for you at no charge.