Quick Answer: A nexus letter is a medical opinion from a physician that states, to at least a 51% probability, that your current condition is related to your military service. It bridges the gap when the VA’s C&P examiner issues an unfavorable or inadequate medical opinion.

What Is a Nexus Letter?

A nexus letter (also called an Independent Medical Opinion or IMO) is a written statement from a qualified medical professional that establishes the connection — or nexus — between your military service and your current disability. The VA uses nexus language to make service connection decisions.

The Magic Language: “At Least as Likely as Not”

VA nexus letters must use specific probabilistic language under 38 CFR § 4.3. The key threshold is “at least as likely as not” — meaning the examiner believes there is at least a 51% probability of the claimed nexus. A letter saying the condition is “possible” or “might be related” does not meet the standard. The letter must say “at least as likely as not” or equivalent language.

When Do You Need a Nexus Letter?

• Your C&P exam produced an unfavorable medical opinion (the examiner said the condition is not related to service)
• You have no in-service treatment records for a condition you know occurred during service
• You are filing for a secondary condition and need to establish the medical link
• Your claim was denied and you believe the denial was based on an inadequate medical opinion

What Makes a Strong Nexus Letter?

A strong nexus letter includes:

• The physician’s qualifications and specialty relevant to the condition
• A review of the veteran’s service records and medical history
• A clear diagnosis of the current condition
• A specific statement using “at least as likely as not” or stronger language
• Medical rationale explaining the basis for the opinion
• Citations to medical literature if applicable

How to Get a Nexus Letter Without Overpaying

Nexus letters from private physicians can cost $500–$2,000 depending on complexity. Unlike general claims assistance (which must be free under SB 694 and federal law for accredited VSOs), nexus letters from private physicians are a separate medical service not covered by VSO assistance. Options for obtaining a nexus letter include:

• Your current treating physician: If you have a doctor familiar with your condition and history, ask them to write a nexus letter. Many will do so as part of your regular care.
• VA treating physicians: VA doctors can write nexus letters supporting your claims. They are not prohibited from doing so.
• Telehealth nexus letter services: Several telehealth platforms specialize in veteran nexus letters at lower cost than traditional specialist rates — typically $200–$500.

Frequently Asked Questions

Can a nexus letter override a C&P exam?

A nexus letter doesn’t “override” a C&P exam — but it creates competing medical evidence that the VA must weigh. Under 38 CFR § 3.303, when there is medical evidence on both sides, the VA must apply the benefit of the doubt in the veteran’s favor (38 U.S.C. § 5107). A well-written nexus letter from a qualified specialist often carries significant weight.

Can a nurse practitioner or PA write a nexus letter?

Yes. The VA accepts nexus letters from any “competent medical professional” — which includes physicians, nurse practitioners, and physician assistants. Specialists in the relevant field carry more weight, but any licensed medical professional can provide a qualifying medical opinion.