What counts as evidence, and what a nexus actually is
Almost nobody is denied because the VA does not believe they are hurt. They are denied because nothing in the file connects the hurt to their service.
Direct service connection rests on three elements: a current diagnosis, an in-service event, injury, or illness, and a medical link between the two. Miss any one of them and the claim fails, no matter how strong the other two are.
In practice, the first two are usually easy. You have a diagnosis; you were in. It is the third, the nexus, that decides most claims. And once service connection is granted, a fourth category of evidence decides the percentage: how severe the condition is and how it affects your life.
That is the structure worth organizing your entire claim around. Four buckets, per condition.
Bucket 1: current diagnosis
You must have the condition now. A knee that hurt in 2011 and healed is not a disability. A knee that hurts today, diagnosed today by a clinician, is.
What works: a diagnosis in a treatment record from a VA, military, or private provider. Specific matters: "chronic lumbosacral strain" is a diagnosis, "back pain" alone historically was not, though the VA now recognizes some pain conditions with functional impairment even absent a named pathology. Get a named diagnosis where you can.
What does not work: your belief that you have a condition, a family member's opinion, or a symptom with no clinician attached to it.
Bucket 2: the in-service event
Something in service has to have happened. It can be:
- An injury, the fall, the blast, the vehicle accident, the parachute landing.
- An illness or symptom onset documented in your Service Treatment Records.
- An exposure, burn pits, Agent Orange, contaminated water, hazardous noise, industrial chemicals.
- The nature of the duty itself, flight line noise, repetitive load-bearing, a body-destroying career field.
Your Service Treatment Records are the primary source, which is why the first thing anyone should do is request their complete STRs and keep a personal copy. But records are not the only proof. Personnel records, performance reports, deployment orders, unit histories, hazard registries, and buddy statements all establish what happened.
A missing STR entry is not fatal. It is an obstacle. Lay statements from people who were there, contemporaneous letters or emails home, photographs, and personnel records documenting your duties can all establish an in-service event the medical record missed. Say so explicitly in your claim rather than hoping a rater infers it.
Bucket 3: the nexus, the link
A nexus is a medical opinion stating that your current condition is connected to that in-service event. It is the piece most claims are missing, and the piece most veterans misunderstand.
The standard is lower than people assume
The VA does not require proof. The legal standard is at least as likely as not, roughly a 50/50 probability. And when the evidence is in equipoise, the benefit of the doubt goes to the veteran by regulation. You do not have to make the case airtight. You have to get it to a coin flip.
What a usable nexus opinion contains
An opinion that helps you generally does four things:
- States the diagnosis plainly.
- Uses the standard language, that the condition "is at least as likely as not" related to the in-service event, or caused or aggravated by an already service-connected condition.
- Shows the reasoning. This is what separates a strong opinion from a weak one. A conclusion with no rationale carries little weight. The examiner should explain the mechanism and reference the specific evidence reviewed.
- Confirms what was reviewed, STRs, current records, your reported history.
A one-line note saying "patient's knee pain likely from military service" is far weaker than a paragraph explaining that repetitive load-bearing over a documented twelve-year infantry career, combined with the documented 2014 knee injury, is a recognized mechanism for the current degenerative changes on imaging.
Where a nexus opinion comes from
- Your treating provider. Often the best source. They already know your history, and a treating relationship carries weight. Many will write one if you ask directly and explain what is needed.
- The VA's own C&P examiner. The exam frequently includes a nexus question. This is free and happens automatically, which is one more reason the exam matters. See the exam guide.
- An independent medical opinion. A private review by an outside physician, usually paid for out of pocket. Worth considering when a C&P examiner returned a negative opinion and you need something to weigh against it, not usually necessary on a first claim.
When you do not need a nexus at all
Two important exceptions:
- Presumptive conditions. For certain exposures and service periods, including conditions added by the PACT Act, Agent Orange presumptives, and Camp Lejeune water contamination, the VA presumes the link if you have the condition and the qualifying service. No nexus opinion required. Check the current presumptive lists on VA.gov, because they change.
- Chronic conditions shown in service. Where a chronic condition was identified in service and there is continuity of symptoms since, the link can be established without a separate opinion.
Bucket 4: severity and functional impact
Service connection gets you in the door at 0%. Severity evidence is what sets the percentage, and this is where most veterans under-document.
Rating criteria in 38 CFR Part 4 are written in specific, measurable terms: frequency of prostrating attacks, degrees of forward flexion, incapacitating episodes per year, whether a breathing assistance device is required. Your evidence should speak the same language.
Symptom logs
Dated entries, written when the symptom happens, describing what occurred and what you could not do. "March 3, migraine from 0900, dark room until 1600, missed the second half of the workday, took sumatriptan" is worth more than "I get migraines a lot." Frequency is a rating criterion; a log is how you prove frequency.
Lay statements
You are competent to report what you experience and observe, and so are the people around you. A spouse describing the nights you do not sleep, a coworker describing the days you leave early, your own account of a flare-up. These are real evidence, not filler. They carry the most weight when they are specific, dated, and consistent with the medical record. VA Form 21-10210 is the standard form; a signed statement works too.
Functional impact
Regulation directs that ratings consider the effect on your ability to function under the ordinary conditions of daily life and work. Say concretely what you cannot do: which tasks at work, which chores, which activities you gave up, what you now need help with. Raters are looking for this and often do not find it.
Conditions that flare are rated on the whole picture, not on the fifteen minutes you spent in an exam room on a good day. If you are asked how you are doing and answer "fine" out of reflex, that is what goes in the record. Answer with your range: the good days, the bad days, and how often each occurs.
Putting it together
Before you submit, walk each condition through the four buckets and name the specific document that fills each one. If you cannot name a document, that bucket is empty, and an empty bucket is a predictable denial or a lower rating, not a surprise.
| Bucket | Question it answers | Typical evidence |
|---|---|---|
| Diagnosis | Do you have it now? | Treatment record naming the condition |
| Service link | Did something happen in service? | STRs, personnel records, buddy statements |
| Nexus | Are the two connected? | Medical opinion, or a presumption |
| Severity & impact | How bad, how often, what does it cost you? | Symptom logs, treatment notes, lay statements |
Filing with all four covered up front, a Fully Developed Claim, also tends to move faster, because there is nothing for the VA to go chase.
READY214 organizes evidence into exactly these four buckets per condition and shows you which one is empty, so nothing gets submitted half-built. Free, no account needed to look.