Nexus Letter for VA Claims: What It Is and How to Get One

A nexus letter is one of the most powerful tools in a VA disability claim. Without a clear connection between your military service and your current condition, the VA will deny your claim. A well-written nexus letter from the right doctor can turn a denied claim into an approved one.

What a Nexus Letter Does

The VA needs to see three things in every disability claim: a current diagnosis, an in-service event, and a connection (nexus) between the two. The nexus letter provides the third element. It tells the VA: this veteran's current condition is medically linked to something that happened during their service.

The Magic Words: "At Least As Likely As Not"

The VA's standard of proof for service connection is the benefit of the doubt — also called the "at least as likely as not" (ALALN) standard. Your doctor does not need to say your condition was definitively caused by service. They only need to say it is 50% or more likely — or "at least as likely as not" — to be connected to service. This is a relatively low bar, and good nexus letters use this exact language.

What a Good Nexus Letter Includes

• The doctor's credentials and license number
• A statement that the doctor reviewed your service treatment records and current medical records
• Your diagnosis
• The specific in-service event or condition being cited as the cause
• Medical reasoning explaining the causal relationship
• The "at least as likely as not" conclusion
• The doctor's signature and date

Who Should Write Your Nexus Letter

The best nexus letter comes from a treating physician who knows your history. A specialist in the relevant field (psychiatrist for PTSD, orthopedist for knee conditions, pulmonologist for respiratory conditions) carries more weight than a general practitioner for complex conditions. Independent Medical Opinions (IMOs) from professional nexus letter services are another option — they typically cost $300–$1,000 but are written by professionals experienced with VA claims language.

When You Don't Need a Nexus Letter

Presumptive conditions: Agent Orange exposures, Gulf War illnesses, radiation exposures, and other presumptives require only the diagnosis and qualifying service — no nexus needed. Clear service records: If your condition was diagnosed and treated during service, the nexus may be obvious. Direct in-service injury: A broken bone documented in your military records doesn't need a nexus letter.

Secondary Service Connection

Nexus letters are especially important for secondary claims — conditions caused or aggravated by a service-connected condition. For example, a doctor writing that hypertension is "at least as likely as not" caused or aggravated by service-connected PTSD is a secondary nexus. The doctor needs to explain the medical relationship between the two conditions.

Frequently Asked Questions

What is a nexus letter for a VA claim?

A nexus letter is a written statement from a medical professional — usually a doctor — that states your current disability is "at least as likely as not" connected to your military service. It bridges the gap between your condition and your time in service.

Who can write a nexus letter?

Any licensed medical professional can write a nexus letter — your primary care physician, specialist, psychiatrist, chiropractor, or any doctor familiar with your condition and service history. It does not have to be a VA provider.

Do I always need a nexus letter?

Not always. For presumptive conditions (like Agent Orange exposures or combat-related conditions), no nexus letter is needed. For conditions clearly documented in service treatment records, the nexus may be obvious. But for secondary claims or conditions not in your records, a nexus letter significantly strengthens the claim.

What is the "at least as likely as not" standard?

The VA uses a 50/50 burden of proof. Your nexus letter only needs to state that it is equally likely or more likely that your condition is service-connected — not certain. This is a relatively low bar compared to other legal standards.