What a Nexus Letter Must Include
Physician Credentials
The letter must identify the physician's medical credentials and specialty. A specialist's opinion (e.g., an orthopedic surgeon for a back claim) carries significantly more weight than a general practitioner.
Review of Your Service Records
The physician must state they reviewed your service treatment records (STRs) and relevant in-service events. Without this, the VA can dismiss the opinion as uninformed.
Current Diagnosis
The letter must confirm a current diagnosis of the condition being claimed. The VA cannot service-connect a condition without a current diagnosis.
The Nexus Statement — "At Least As Likely As Not"
The physician must state the condition is "at least as likely as not" (50% or higher probability) caused by, related to, or aggravated by in-service events or an existing service-connected condition. These specific words meet the VA's "approximate balance of positive and negative evidence" standard under 38 CFR §3.102.
Rationale
The best letters explain why there's a nexus — citing medical literature, the veteran's specific service history, or known mechanism of injury. A bare conclusion without reasoning is easier for the VA to reject.
How to Ask Your Doctor
Types of Nexus
Direct Service Connection
The condition was caused by an in-service event, injury, or exposure. Example: knee injury during training.
Secondary Service Connection (38 CFR §3.310)
The condition was caused or aggravated by an already service-connected condition. Example: PTSD → sleep apnea. The nexus connects the secondary condition to the primary.
Aggravation
A pre-existing condition was made permanently worse (beyond natural progression) by military service. Requires baseline evidence of pre-service severity and documentation of in-service aggravation.
Frequently Asked Questions
Can any doctor write a nexus letter?
Yes — any licensed physician can write a nexus letter. However, a specialist's opinion carries more weight with VA raters. For complex conditions, it's worth seeking a physician who has experience writing VA nexus letters. Telehealth services specializing in veteran nexus letters are also available.
What if my doctor won't write one?
Find a different doctor. No physician is obligated to write a nexus letter. Many primary care doctors are unfamiliar with VA claim requirements — a specialist or a doctor familiar with veteran healthcare is usually a better choice. Your VSO can also provide guidance.
Does a nexus letter guarantee approval?
No — but it dramatically improves your odds. The VA must weigh the nexus letter against any negative evidence (like a C&P examiner opinion). A strong, well-reasoned nexus letter from a credentialed specialist is difficult for the VA to overcome.
Is a Disability Benefits Questionnaire (DBQ) the same as a nexus letter?
No — but a DBQ plus a nexus letter together are extremely powerful. A DBQ documents the severity of your condition (for rating purposes). The nexus letter establishes the connection to service. For a new claim, you ideally want both.