The conversation goes about the same way every time.
A veteran has a service-connected knee. Years of walking wrong on it wrecked the other knee, then the lower back. They mention it almost as an aside, because as far as they know it is not a claim. Nothing happened to their back in service. There is no back injury in their service treatment records. Whatever the VA process is, they assume it starts with something that happened in uniform, and their back does not have that.
That assumption costs veterans more money than almost any other single misunderstanding of this system.
The back is a claim. It has been a claim the entire time.
What the rule actually says
The regulation is 38 C.F.R. § 3.310, and the operative sentence is short. A disability that is proximately due to or the result of a service-connected disease or injury shall be service connected.
Three elements:
- A current diagnosis of the new condition.
- A disability VA has already service connected.
- Medical evidence linking the two.
Read the list again for what is not on it. There is no in-service element. No injury during service, no complaint at sick call, no entry in your service treatment records, no symptom at separation, no continuity from discharge to today.
Direct service connection asks what happened to you in service. Secondary service connection does not ask that question at all. It was already answered when VA granted the first condition. The only question left is what that first condition has done to you since.
The service-connected condition can be rated at 0 percent
This one changes claims regularly.
The rule requires the first condition to be service connected. It says nothing about the percentage. A noncompensable rating means VA agreed the condition is connected to your service and found it does not currently meet the criteria for a paying evaluation. The grant is still a grant.
If you have a 0 percent rating sitting in your decision letter that you long ago stopped thinking about, it is a live foundation for a secondary claim. That is one of the reasons to challenge a 0 percent rating rather than shrug it off, which we covered in VA’s Own Watchdog Found Half of These 0 Percent Joint Ratings Were Wrong.
The rule has two halves, and most veterans only know the first
Caused by. Section 3.310(a) covers the straightforward version. The service-connected condition produced a new one that would not otherwise exist. A service-connected knee changes how you walk, the altered gait loads the spine unevenly for fifteen years, and now there is a lumbar condition.
Made worse. Section 3.310(b) covers something different and far less known. You already had a condition. It was not related to service and it never would have been. Then a service-connected disability made it worse. The regulation service connects the increase in severity, even though the underlying condition stays nonservice connected.
The second half matters because veterans rule themselves out under it constantly. Someone with pre-existing arthritis, or diabetes that runs in the family, or a bad shoulder from a civilian job, hears that the condition is not related to service and concludes there is nothing to file. Under 3.310(b), whether the condition is related to service is not the question. The question is whether a service-connected disability has made it worse than it would otherwise be.
There is a mechanical piece to the aggravation half. You are paid for the amount of worsening above where the condition stood before the aggravation started, not for the whole condition. The regulation calls that earlier level the baseline, and it requires the baseline to be established by medical evidence, either from before the aggravation began or from the earliest medical evidence available after it. A deduction has to rest on that evidence. It is not something an adjudicator gets to estimate.
What the link has to look like
Element three, the medical link, is where nearly every one of these claims is won or lost.
VA does not need certainty. The standard is whether it is at least as likely as not that the service-connected condition caused or aggravated the new one. If the evidence for and against sits in equipoise, the benefit of the doubt goes to you under 38 U.S.C. § 5107(b).
What that requires in practice is an opinion from a clinician that does two things: states the conclusion in those probability terms, and explains the reasoning behind it. A letter that says your back pain is related to your military service is not the opinion a secondary claim needs, and it is one of the most common problems in these files. The question is not whether the back is related to service. It is whether the back is related to the knee.
An adequate secondary opinion should also address both halves of the rule. If the clinician answers only causation and never reaches aggravation, half the claim went undecided. That gap appears constantly in VA examination reports, because the examiner was only ever asked the causation question. More on what separates an adequate opinion from an inadequate one is in The Exam Is the Appointment. The Opinion Is What Decides the Claim.
The relationships that come up most
These are not the only ones, and no list of pairings decides an individual claim. They are the patterns that show up most often in files.
Orthopedic chains. A service-connected joint changes your mechanics, and the joints doing the compensating wear out. Knee to opposite knee. Knee or ankle to hip and lower back. Shoulder to neck. These claims turn on a clinician explaining the mechanism, not on the pairing being familiar.
Mental health from physical conditions. Chronic pain, lost mobility, lost independence, and lost work produce depression and anxiety. This is one of the most under-filed secondary claims in the system, and it is frequently the one that moves a file toward TDIU.
Physical conditions from mental health. The relationship runs the other direction too. Sleep disorders, gastrointestinal conditions, and hypertension are all claimed as secondary to service-connected PTSD or depression.
Downstream disease processes. Peripheral neuropathy, retinopathy, and kidney disease secondary to service-connected diabetes.
Medication and treatment. A condition caused by the treatment for a service-connected disability is secondary to that disability. Years of anti-inflammatory medication for a service-connected knee produce a gastrointestinal condition. The claim is not that the knee caused the reflux. It is that the treatment the knee required did.
Surgical and residual effects. Scars, nerve damage, and loss of function following surgery on a service-connected condition.
There is also a smaller category the regulation handles for you. Section 3.310 provides that certain conditions following a service-connected traumatic brain injury are held to be secondary to it when they appear within specified periods, including parkinsonism and unprovoked seizures after moderate or severe TBI, certain dementias within fifteen years, depression within three years of moderate or severe TBI or twelve months of mild TBI, and hormone deficiency diseases within twelve months. If that describes your history, the link is written into the rule rather than something you have to establish.
Secondary to a secondary is still secondary
Nothing in the regulation limits the chain to a single link.
Diabetes gets service connected. Peripheral neuropathy gets connected as secondary to the diabetes. The neuropathy causes a fall, the fall injures a shoulder, and the shoulder is connectable as secondary to the neuropathy. Each link needs its own medical support, but the chain does not have a length limit and it does not have to run back to something in your service records.
Filing will not cost you what you already have
The fear that stops these claims is pyramiding. Veterans have heard that claiming related conditions can backfire, and they leave the second claim unfiled.
38 C.F.R. § 4.14 bars evaluating the same disability under different diagnoses. If a single symptom is already being paid for under one rating, it cannot be paid for again under a second one. That is the whole rule.
It does not bar claiming a genuinely separate condition, even one in the same region of the body or arising from the same original injury. A service-connected knee rated on limitation of motion and a separate rating for instability of that knee are two different impairments, not one impairment counted twice. A lumbar spine condition secondary to a knee is not the knee.
Filing a claim for a new condition is also not a request to revisit the ratings you already hold, and VA does not treat it as one.
Effective dates work differently than people expect
A secondary claim generally starts its own clock. The effective date is the date VA received that claim or the date entitlement arose, whichever is later. It does not reach back to the effective date of the primary condition just because the primary came first.
The practical consequence is direct. A veteran who has been treating a secondary condition for eight years and files this month is generally looking at benefits from this month. Those eight years are gone, not because the condition was not connected, but because no claim was pending.
Two things soften that in specific situations. If the secondary condition was reasonably raised in a claim that is still open, it belongs to that claim rather than to a new one. And an intent to file holds your date for a year while you gather what you need. Effective dates are the part of this system where timing does the most damage, and they are covered across several posts here, including The One-Year Lookback and Unadjudicated Claims.
Why the arithmetic favors secondary claims
Veterans who want a higher combined rating usually push on the conditions they already have, asking for an increase on a knee that has been rated 10 percent for a decade. Sometimes that is right. Often the better available move is a condition that is not in the file at all.
Increases are capped by the rating criteria for that diagnostic code. A new service-connected condition is not competing for room inside those criteria. And because combined ratings are not addition, the effect of a new grant depends on where it lands. Two well-supported secondary conditions can do more for a combined rating than years of arguing about a single percentage.
Secondary conditions also matter for reasons other than the percentage. Mental health conditions secondary to physical disabilities are one of the common routes to TDIU, and secondary grants can affect eligibility for special monthly compensation and dependent benefits.
Where these claims get denied
Four patterns account for most of it.
The opinion answered the wrong question. The clinician addressed whether the condition relates to service instead of whether it relates to the service-connected disability. Denied for no nexus, when the nexus that mattered was never discussed.
The examiner was never asked about aggravation. The examination request posed the causation question only. The report says the condition was not caused by the service-connected disability, says nothing about whether it was made worse, and the decision denies on that record. Half the regulation went unaddressed.
VA applied the direct service connection test. The denial explains that there is no evidence of the condition in your service treatment records and no continuity of symptoms since discharge. Both statements can be entirely true and neither one has anything to do with 3.310. If your decision letter denies a secondary claim without ever discussing the service-connected condition it was filed as secondary to, that is a decision that answered a question you did not ask.
The opinion was a conclusion with no reasoning. A single sentence saying the conditions are unrelated, with no explanation, is not adequate evidence, and an inadequate examination is grounds to challenge the decision built on it.
What to do with this
- List every rating you hold, including the 0 percent ones. That list is the set of foundations available to you.
- List every health problem you have now, service connected or not, and put the two lists side by side. You are looking for anything that started after, or got worse after, a condition on the first list.
- For anything already diagnosed before the service-connected condition, do not stop. That is the aggravation half of the rule, and it is the half most veterans never file under.
- Get the opinion aimed at the right question. The clinician needs to address whether the service-connected condition caused or aggravated the new one, in probability terms, with reasoning. Not whether the new condition is related to your service.
- File when the condition appears, not when it becomes unbearable. The effective date is generally the filing date, and waiting is the most expensive habit in this process. An intent to file holds your place while you assemble evidence.
- If you were denied, read the reasons and bases against the regulation. Check whether VA discussed the service-connected condition at all, and whether anyone addressed aggravation.
Whether any particular claim succeeds depends on the evidence, the diagnoses, and how the file is built. Nobody can tell you your outcome. But the veteran who assumes the new condition is not a claim because nothing happened in service is answering a question the regulation does not ask.
Blackmore Veterans Law, P.C. is a solo practice representing veterans in VA disability claims and appeals. Contact us to discuss your situation.
This article is general information about VA disability law and is not legal advice for any individual case. Reading it does not create an attorney-client relationship. Attorney advertising.