How to Write a VA Nexus Letter (Doctor's Guide)

What Every Nexus Letter Must Include

• Provider credentials and statement of qualification to give the opinion.
• Records reviewed (specifically list STRs, VA records, private records).
• Current diagnosis with diagnostic criteria.
• Clear nexus statement using the exact phrase 'at least as likely as not (50% or greater probability).'
• Rationale that explains the medical reasoning, not just the conclusion.
• Citation of supporting medical literature for non-obvious connections.
• Provider signature, license number, and date.

The Language the VA Looks For

VA examiners are trained to weigh opinions against four standards: 'is due to' (100%), 'more likely than not' (>50%), 'at least as likely as not' (=50%, the winning threshold), and 'less likely than not' (<50%). Anything below 50% loses. The phrase 'at least as likely as not' is the magic minimum.

Rationale Matters More Than the Conclusion

VA raters discount opinions that lack reasoning. A two-sentence nexus letter saying 'I have reviewed the records and find the condition is at least as likely as not service-connected' will lose to a contradicting C&P opinion. A two-page rationale citing the in-service event, current pathology, and published medical literature can win.

Nexus Letters for Secondary Claims

For secondary service connection, the opinion must address either causation OR aggravation: 'It is at least as likely as not that the veteran's [secondary condition] was caused by — or has been aggravated beyond its natural progression by — the service-connected [primary condition].'

A Simple Structure That Works

A strong nexus letter generally follows a predictable structure: introduce the provider's qualifications and records reviewed, state the current diagnosis, present the nexus conclusion using the correct standard language, then walk through the specific medical reasoning connecting the two — citing literature where the connection isn't already obvious from the record alone. Providers unfamiliar with VA claims sometimes skip straight from diagnosis to conclusion, which is exactly the gap that weakens an otherwise valid opinion.

Common mistakes to avoid

• Using 'possible' or 'could be related' — these don't meet the 50% threshold.
• No rationale, just a conclusion.
• Provider with no claim of qualification to opine on the specific condition.
• Missing the aggravation alternative in secondary claims.

Frequently asked questions