A useful VA nexus letter example shows the reasoning a clinician has to supply: which records they reviewed, which facts cut against the connection, and why their conclusion still holds or does not. The three annotated examples below use fictional claim files and mark where the clinician's own words belong. Each one sits next to a short passage from a public Board of Veterans' Appeals decision that shows how the Board weighed a real opinion on the same kind of theory.

A blank, printable template follows. It asks the medical questions and leaves every answer to the clinician. If you are still deciding whether you need a letter at all, start with what a nexus letter is and when you might need one.

Three theories, three different questions

TheoryQuestion the clinician answersRecords that matter mostWhere opinions usually fall short
DirectIs the current condition linked to an event, injury, disease or exposure in service?Service treatment record, current diagnosis, treatment history, later injuriesMissing or misstating the in-service record; ignoring a later injury or a long gap
Secondary causationDid a service-connected condition cause the second condition?Primary-condition history, second diagnosis, medications, other risk factorsCiting an association in research without applying it to this person
AggravationDid a service-connected condition worsen the second condition beyond its natural progress?A dated baseline record, later severity, other explanationsDescribing current severity without a baseline, or answering only causation

Direct service connection is governed by 38 C.F.R. § 3.303. Secondary causation and aggravation are both in 38 C.F.R. § 3.310, paragraphs (a) and (b).

Example 1: direct service connection

The file (fictional): Avery has lumbar degenerative disc disease shown on a 2024 MRI. A May 2009 service treatment note records low back pain after a vehicle rollover during a convoy. Treatment is sparse from 2011 to 2017. A 2018 urgent care note records a lifting injury at a civilian job. A 2023 VA examiner gave a negative opinion and wrote that the service treatment records show no back complaints.

What the clinician's letter has to contain (clinician's words go in the brackets):

Records reviewed: [Each record by date: the May 2009 service treatment note, the 2018 urgent care note, the 2024 MRI report, the 2023 VA examination, and the treatment notes actually read.]

Facts that cut against the connection: [How the clinician weighed the 2018 lifting injury and the years with little treatment.]

The earlier negative opinion: [Whether the 2023 examiner's premise, that service records show no back complaint, matches the May 2009 note, and what follows from that.]

Opinion and reasoning: [The clinician's own conclusion, at the level of certainty they can support, and the medical explanation connecting the facts to it.]

Questions to ask when you read the finished letter:

  • Does it name the May 2009 record, or only say the file was reviewed?
  • Does it explain why the 2018 injury does or does not account for the current findings?
  • Does it answer the factual premise of the earlier negative opinion instead of ignoring it?

In the Board's words: In a March 26, 2025 decision (Citation A25028065), the Board granted service connection for a back disability. It relied on a private physician assistant's opinion that tied the condition to a documented in-service motor vehicle accident, finding that the examiner "provided adequate rationale and relied on an accurate history." The Board gave no probative value to two VA opinions, one of which relied "on an inaccurate factual premise": that the service treatment records showed nothing about the back.

Example 2: secondary causation

The file (fictional): Jordan is service connected for an anxiety disorder with chronic sleep impairment, rated since 2019. Gastroesophageal reflux disease (GERD) was diagnosed in 2023 after about a year of heartburn. The records also show a 30-pound weight gain in 2021 and daily ibuprofen for a knee. A VA examiner's negative opinion said research shows only an association between anxiety and reflux.

What the clinician's letter has to contain:

Primary condition: [The service-connected anxiety disorder and the symptoms documented, with dates.]

Second condition: [The GERD diagnosis, its date, and the record that made it.]

Sequence: [When reflux symptoms began compared with the anxiety disorder and sleep problems.]

Mechanism: [Whether and how the anxiety disorder or its symptoms could cause GERD in this person, and how any cited study applies to Jordan's history.]

Other causes: [How the clinician weighed the weight gain and the daily ibuprofen.]

Aggravation, answered separately: [If the clinician does not find causation, whether the anxiety disorder worsened the GERD beyond its natural progress.]

Opinion and reasoning: [The clinician's own conclusion and explanation.]

A list of studies is not the reasoning. The letter has to apply the mechanism to Jordan's timeline and say why the competing explanations do or do not change the answer.

In the Board's words: In a January 28, 2025 decision (Citation A25007304), the Board granted service connection for GERD as secondary to a service-connected anxiety disorder. It gave a private nurse practitioner's opinion significant probative weight because she "provided a detailed rationale" that explained a multi-step causal chain and cited supporting studies. It gave the VA examiner's negative opinion little weight: the examiner did not discuss the evidence the private opinion relied on. "Nor did the VA examiner address the question of whether the Veteran's anxiety disorder aggravated his GERD."

Example 3: aggravation and the baseline rule

The file (fictional): Casey has migraines that are not service connected. A 2018 neurology note records about two migraine days a month on one preventive medication. Casey is service connected for a cervical strain that flared in 2022. By 2024, neurology notes and a headache log record eight to ten migraine days a month and a second preventive medication. Casey also started night shifts in 2023 and uses more over-the-counter pain relievers.

VA will not concede aggravation unless the baseline severity of the non-service-connected condition is established by medical evidence created before the aggravation began, or by the earliest medical evidence created between the onset of aggravation and the evidence showing its current severity. VA then subtracts the baseline, and any worsening from the condition's natural progress, from the current level. That rule is in 38 C.F.R. § 3.310(b). Here, the 2018 neurology note may serve as the baseline. The clinician and VA decide whether it qualifies. The Federal Circuit held in Spicer v. McDonough (2023) that compensation under 38 U.S.C. § 1110 covers any additional impairment a service-connected disability causes, including a condition that is worse than it would otherwise be, and that § 3.310(b) cannot be used to reject that kind of claim. A dated baseline record still helps the clinician explain how much of the current severity the service-connected condition added.

What the clinician's letter has to contain:

Baseline: [The dated medical record relied on for severity before the worsening, and what it shows.]

Current severity: [The dated records showing the current level.]

Natural progress: [How much change the migraine condition itself would be expected to show over that period.]

Other explanations: [How the night-shift schedule, medication use and other triggers were weighed.]

Opinion and reasoning: [Whether the neck condition worsened the migraines beyond natural progress, and why.]

In the Board's words: In a November 14, 2023 decision (Citation A23031938), the Board remanded a claim for sleep apnea as secondary to a service-connected adjustment disorder with depressed mood. The VA opinion addressed causation, but "no opinion was provided regarding the aggravation theory." The Board told the next examiner, if aggravation occurred, to say when it began and whether the file "contains sufficient medical evidence created before the onset of aggravation to establish a baseline level of severity." A remand is not a grant. It sent the question back for a complete opinion.

A printable clinician review template

Print this page or copy the block below, attach your dated record index, and give both to the clinician. The first five items are yours to fill in. The rest belong to the clinician.

Request for a medical opinion for a VA disability claim

Patient name: ______________________ Date of request: ______________

1. Question(s) to answer (check each one you are asking about)

[ ] Direct: Is [current condition] at least as likely as not related to [in-service event, injury, disease or exposure, with date]?

[ ] Secondary causation: Is [condition] at least as likely as not caused by service-connected [condition]?

[ ] Aggravation: Is [condition] at least as likely as not aggravated beyond its natural progress by service-connected [condition]?

2. Records provided (date, record, page): ______________________

3. Facts that may cut against the connection: ______________________

4. Earlier opinions in the file and what they concluded: ______________________

5. Baseline record (aggravation only): the earliest medical record showing severity before the worsening: ______________________

For the clinician

6. Records you reviewed: ______________________

7. Your opinion on each checked question, in your own words: ______________________

8. Your reasoning, including how you weighed item 3 and any research you relied on: ______________________

9. Limits: missing records or questions you could not answer: ______________________

10. Name, credentials, specialty, relationship to the patient, signature and date: ______________________

Leave items 7 and 8 blank when you hand it over. The opinion has to be the clinician's own medical judgment, and the clinician may reach a conclusion that does not support the claim.

Check the letter against its records

When the letter comes back, compare every date and fact it cites with the record itself. How to review a nexus letter walks through that check and shows how opinion quality lined up with outcomes across Claim Raven's Board decision data. If you are deciding whether to pay a service for a letter, the nexus letter cost comparison compares companies by screening fees, letter prices, add-ons and refund terms.

Raven Nexus can check a letter you already have, or organize selected records and research into an editable draft and question list for your clinician. A free account includes one starter assessment; full drafts need Standard or Plus. No clinician or signature is included. Claim Raven sells this tool, so it has a commercial interest in your choice.

Sources and scope

Checked September 23, 2026: 38 C.F.R. § 3.303 and 38 C.F.R. § 3.310 on eCFR, including the paragraph (b) baseline rule; Board decisions A25028065 (March 26, 2025, granted), A25007304 (January 28, 2025, granted) and A23031938 (November 14, 2023, remanded). Each Board decision applies only to its own record. The three claim files are fictional and deliberately include facts that cut against the claim; the bracketed sections are unfinished on purpose, because the medical opinion has to come from the clinician.