Service connection does not stop at the first condition. When a condition the VA has already service connected causes or worsens a second condition, that second condition can be service connected too. The VA calls this secondary service connection, and claims built on it are usually just called secondary claims. This guide explains what the rule actually says, what a secondary claim turns on, and what happens to your rating if one is granted. It explains the system; it does not tell you what to file. Whether a secondary claim makes sense in your situation is a conversation for your free accredited VSO.
What "secondary" means
The regulation is 38 CFR 3.310, and its core sentence is short: a disability that is proximately due to, or the result of, a service-connected disease or injury shall be service connected. "Proximately due to" is the legal phrasing for a direct causal chain: the service-connected condition led to this one.
The point of the rule is that the VA compensates the consequences of service, not just the injuries that happened in uniform. A condition that developed years after discharge can still be service connected if the chain runs through a condition that already is. When granted, the secondary condition is treated as part of the original condition for compensation purposes, which in practice means it gets its own rating like any other service-connected disability.
The aggravation rule
The same regulation covers a second situation: a service-connected condition that does not cause a new disability but makes an existing, nonservice-connected one worse. That is aggravation, and the VA compensates the degree of worsening beyond what the condition would have done on its own, its "natural progress."
Aggravation cases involve a baseline: the VA looks at how severe the nonservice-connected condition was before the aggravation and how severe it is now, and the compensable part is the difference. That makes dated records from before and after especially important in these claims, which is one more reason a dated symptom journal and an organized medical file earn their keep.
The three things at issue
Stripped to its parts, a secondary claim generally turns on three things:
- A current disability. A diagnosed condition, documented in medical records.
- An existing service-connected condition. The one you believe did the causing or the worsening. Your most recent decision letter lists what is service connected and at what percentage; if you are not sure how to read it, see how to read your VA decision letter.
- A link between the two.Medical evidence connecting the service-connected condition to the claimed one. This link, often called a nexus, is usually where secondary claims are won or lost, and it is medical territory: a treating provider's records or opinion, not a veteran's own assertion.
How a secondary claim is filed
There is no special secondary-claim form. It is a disability compensation claim like any other, filed on VA Form 21-526EZ: online at VA.gov, by mail, in person at a regional office, or through an accredited representative. The claim identifies the condition being claimed and the service-connected condition it stems from.
Everything that applies to an original claim applies here: the VA may schedule a C&P exam, the claim moves through the same stages, and an accredited VSO can prepare and file it with you for free.
How the new rating combines
A granted secondary condition gets its own percentage, and that percentage joins your existing ratings through the VA's combined ratings table. The table is not addition: 50 and 30 do not make 80. If the arithmetic has ever surprised you, the whole system is walked through in how VA combined-rating math works, and you can run your own numbers in the combined rating calculator.
The evidence that matters
Because the causal link carries the claim, the useful evidence is the kind that documents the chain:
- Medical records for the claimed condition, showing diagnosis and treatment.
- Records for the service-connected condition, which establish the starting point of the chain.
- A medical opinion connecting them, when a provider is willing to state one in the record.
- Dated symptom history. When the second condition started and how it has tracked against the first one. This is exactly what a symptom journal preserves and memory does not.
What does not carry a secondary claim by itself is the veteran's own conclusion that one condition caused the other. The belief may well be right; the claim still needs the medical record to say it.
Effective dates, briefly
The effective date, the day your compensation is calculated from, is generally tied to when the VA receives the claim. The exact rules have exceptions and the VA's effective date page lays them out; your decision letter will state the date used. If a grant comes with months of back pay, the back pay calculator shows how the published rates turn an effective date into a number.
The file this claim is built from
A secondary claim reaches across your whole medical history: old decision letters, records for two conditions, and a dated account of when things changed. Veterans who can put their hands on all of that in one sitting file better claims with less misery. MusterVault keeps every document encrypted and organized on your own computer, with the symptom journal alongside, so the day you and your VSO decide to file, the evidence is already in one place. The organizing is our job; the advice is theirs.