What a VA nexus letter is and why it matters
A nexus letter is a written medical opinion from a qualified provider that links your current condition to your military service. For most claims that are not presumptive, it is the piece of evidence VA weighs most heavily, because it answers the central question: is this condition at least as likely as not related to service? This free tool generates a clean template you can hand your doctor, written around your details, so the opinion and rationale they provide are easy to complete.
Who this helps
Veterans who have a diagnosis and an in-service event but need a medical opinion connecting the two. Veterans filing a secondary claim that needs a causal or aggravation link. Anyone who was denied for a missing nexus and wants to give their doctor a clear starting point.
When to use it
Use it once you have a current diagnosis and can describe the in-service event or the service-connected primary condition. Generate the template, then bring it to a provider who knows your history. Presumptive conditions usually do not need a nexus letter, since VA presumes the connection.
Why the medical opinion and rationale matter
VA looks for the phrase at least as likely as not, meaning a 50 percent or greater probability. But the language alone is not enough. The strongest letters include a clear medical rationale, the because that explains the link, referencing your records, exam findings, continuity of symptoms, and accepted medical principles. The opinion has to be your provider's own; this template simply makes their job easier.
What this tool helps you organize
It assembles your name, condition, the in-service event, and any primary condition into a structured letter with the standard opinion language and a placeholder for your doctor's rationale. It also gives you a checklist of what makes a nexus opinion strong, so nothing critical is left out.
Related Vet Claims Guide tools
Map a primary condition to possible secondary claims with the Secondary Conditions Mapper, organize the rest of your records with the Condition Evidence Builder, and if you were denied, find your path with the Appeal & Next-Steps Finder.
Frequently asked questions
A nexus letter is a written medical opinion from a qualified provider stating that your condition is at least as likely as not connected to your military service. It is often the deciding piece of evidence for service connection.
A qualified medical professional who has reviewed your history, such as your treating physician, a specialist, or a private provider. Vet Claims Guide does not write the opinion; this template helps your doctor write theirs.
It means a 50 percent or greater probability that your condition is related to service. That is the level of certainty VA looks for in a supporting medical opinion.
Usually no. For presumptive conditions such as the PACT Act or Agent Orange, VA presumes the service connection, so a separate nexus letter is generally not required.
A clear diagnosis, the at least as likely as not language, and most importantly a medical rationale explaining why the condition is linked to service, referencing records, exam findings, and accepted medical principles.