If you’re gathering evidence for a VA disability claim, you’ve probably heard of the “nexus letter.” This single document can be a critical piece of clinical evidence in your file—providing the medical documentation necessary to clarify the relationship between your service and your current diagnosis.
But what is a nexus letter, and what makes one clinically effective?
A nexus letter is a medical opinion from a qualified professional that directly links your disability to your time in service based solely on clinical judgment. It’s the medical link that connects the dots for the VA, showing that your condition is “at least as likely as not” (the 50% standard) related to your military service.
This guide will walk you through exactly what a strong nexus letter needs, who can write one, and three distinct examples you can use as a reference for medical documentation.
What Makes a Nexus Letter Clinically Sound? The 4 Crucial Elements
A weak nexus letter just states a vague opinion. A strong nexus letter provides a well-reasoned clinical rationale. It must include these four elements:
- The Right Credentials: The letter must be from a qualified medical expert. A general practitioner can write one, but a letter from a specialist (e.g., an orthopedic surgeon for a back condition, a psychologist for PTSD) provides expertise in documenting symptoms and limitations. The letter should clearly state their title and expertise.
- A “Review of Records” Statement: This is non-negotiable. The expert must state that they have thoroughly reviewed your service medical records (SMRs), VA health records, private medical records, and any other relevant documents. This shows their clinical opinion is based on medical evidence.
- A Clear Medical Opinion (Clinical Terminology): The letter must use specific clinical language that the VA recognizes. The standard medical-legal threshold is:
- “It is at least as likely as not (a 50% or greater probability) that [Your Condition] was caused by or aggravated by [Event in Service].”
- Other strong phrases include: “is proximately due to” or “was directly caused by.”
- Weak phrases to avoid: “could be,” “might be,” or “is possibly related to.”
- A Detailed Medical Rationale: This is the “why.” The expert must explain how they reached their conclusion. They should cite specific medical principles, research studies, or evidence from your records that supports the link. If it’s a secondary condition, they must explain the medical pathway (e.g., “The veteran’s service-connected knee injury caused an altered gait, which, in turn, placed excessive stress on his left hip, leading to degenerative arthritis.”).
Who Can Provide Your Nexus Letter?
- Your VA Doctor: This can be difficult, as some VA doctors are hesitant to provide opinions for claims. However, it doesn’t hurt to ask for an evaluation.
- Your Private Doctor/Specialist: This is often an excellent option, as they have an established relationship with you.
- Private Medical Evaluation Services: These are professionals who provide medical evaluations and nexus letters based solely on clinical judgment. These services focus on documenting symptoms, diagnoses, and functional limitations in full compliance with regulations like SB 694.
3 Nexus Letter Examples
Note: These are simplified examples for educational purposes. A real letter would be more detailed, often spanning multiple pages, and focused on clinical findings.
Example 1: Direct Service Connection (Plantar Fasciitis)
To: VA Regional Office
From: Dr. Jane Doe, DPM (Doctor of Podiatric Medicine)
Re: Nexus Letter for John Veteran, SSN: XXX-XX-XXXX
“I have treated Mr. John Veteran for bilateral plantar fasciitis since 2023. I have conducted a thorough review of his records, including his Service Medical Records from his time in the U.S. Army (2010-2016) and his private treatment notes.
His SMRs document multiple complaints of foot pain and visits to sick call during basic training and after long ruck marches. His MOS as an 11B (Infantryman) required constant standing, walking, and running on hard, uneven terrain while carrying heavy loads, all of which are well-known risk factors for plantar fasciitis.
It is at least as likely as not (a 50% or greater probability) that Mr. Veteran’s current, chronic bilateral plantar fasciitis was incurred in and caused by his active-duty service as an Infantryman.”
Example 2: Secondary Service Connection (Sleep Apnea secondary to PTSD)
To: VA Regional Office
From: Dr. Alex Smith, MD (Board-Certified in Sleep Medicine & Psychiatry)
Re: Nexus Letter for Jane Veteran, SSN: XXX-XX-XXXX
“I am Ms. Jane Veteran’s treating psychiatrist for her service-connected PTSD (VA Claim #XXXXXX). I have also reviewed her 2024 sleep study, which confirmed a diagnosis of moderate obstructive sleep apnea (OSA).
I have reviewed Ms. Veteran’s complete medical file. There is significant medical literature establishing a strong link between PTSD and the development of OSA. The physiological hyperarousal in PTSD can affect upper airway stability during sleep. Furthermore, the weight gain commonly associated with PTSD and its related medications (which Ms. Veteran has experienced) is a major risk factor for OSA.
Therefore, it is at least as likely as not that Ms. Veteran’s obstructive sleep apnea is proximately due to and a secondary result of her service-connected PTSD.”
Example 3: Service Connection by Aggravation
To: VA Regional Office
From: Dr. Michael Chen, MD (Orthopedic Surgeon)
Re: Nexus Letter for John Veteran, SSN: XXX-XX-XXXX
“I am writing regarding Mr. Veteran’s claim for his right knee. I have reviewed his file, including his entrance physical (MEPS) from 2012, which shows a pre-existing ‘stable’ right knee ACL tear.
His SMRs document that during a training exercise in 2014, he jumped from a vehicle and re-injured this knee, resulting in a new meniscal tear and documented ‘chronic instability.’ His pre-service condition was noted as asymptomatic and stable. His military service permanently worsened this underlying condition beyond its natural progression.
It is my medical opinion that Mr. Veteran’s current right knee disability was aggravated by his active-duty service beyond the natural progression of the pre-existing injury.”
Final Steps
A clinically sound nexus letter is a thorough medical document. When you submit evidence for your claim, this letter provides a professional medical opinion to be considered alongside your other records. If you have been previously denied based on a lack of medical evidence, a new nexus letter providing additional clinical rationale can be submitted as new and relevant evidence.