How to file a VA secondary service connection claim — 38 CFR 3.310, the aggravation baseline rule, the nexus opinion, and how the new rating combines
Under 38 CFR 3.310 a disability that is proximately due to or the result of a service-connected disease or injury is service-connected, and so is any increase in a non-service-connected condition caused by a service-connected one, beyond its natural progress. The second route — aggravation — requires medical evidence of the condition's baseline severity before the aggravation began, because VA rates only the increase. Two presumptions help specific veterans: cardiovascular disease after a service-connected amputation of a leg at or above the knee (or both legs at or above the ankles), and after a service-connected traumatic brain injury, parkinsonism, unprovoked seizures, certain dementias, depression and hormone-deficiency diseases within set periods. Everything else turns on a medical nexus opinion that it is at least as likely as not that the service-connected condition caused or aggravated the new one. A secondary condition gets its own rating, combined with your others under 38 CFR 4.25.
What you'll need
- VA Form 21-526EZ (or VA Form 20-0995 Supplemental Claim if VA denied the condition before)
- Your rating decision showing the service-connected primary condition
- Medical records diagnosing the secondary condition; for an aggravation claim, records showing its severity before the aggravation began
- A written nexus opinion from a physician or other qualified clinician, with a rationale
- A free accredited representative (CVSO or VSO)
Step-by-step
Step 1: Identify the link — causation or aggravation
Causation (3.310(a)): the service-connected condition, or its treatment, produced the new condition — for example a gait change from a service-connected knee that leads to hip or back problems, or a medication side effect. Aggravation (3.310(b)): a condition you would have had anyway was made worse by the service-connected one; VA will not concede aggravation unless the baseline severity is shown by medical evidence created before the aggravation began (or the earliest evidence after it), and it rates the difference between the current and baseline levels minus natural progress. The exception in 38 CFR 3.300(c) bars secondary service connection for disability from tobacco use.
Step 2: Check the two presumptions in 3.310(c) and (d)
Cardiovascular disease, including ischemic heart disease, is presumed secondary to a service-connected amputation of one leg at or above the knee or of both legs at or above the ankles. After a service-connected TBI, VA presumes, absent clear evidence to the contrary: parkinsonism and unprovoked seizures following moderate or severe TBI; Alzheimer-type presenile dementia, frontotemporal dementia and dementia with Lewy bodies within 15 years of moderate or severe TBI; depression within 3 years of moderate or severe TBI or within 12 months of mild TBI; and hormone-deficiency diseases from hypothalamic-pituitary changes within 12 months of moderate or severe TBI. TBI severity is judged at the time of injury by the criteria in 3.310(d)(3).
Step 3: Get the nexus opinion right
Ask a VA or private clinician for a signed statement that (1) diagnoses the secondary condition, (2) states that it is "at least as likely as not" — a 50 percent or greater probability — that the service-connected condition caused it, or aggravated it beyond its natural progress, and (3) explains why, citing your records and medical literature. The standard comes from VA's benefit-of-the-doubt rule (38 CFR 3.102). For aggravation, the opinion should identify the baseline severity and the current severity. Opinions without a rationale carry little weight.
Step 4: Word the claim and file it
On VA Form 21-526EZ list the condition as "[condition], secondary to service-connected [primary condition]" so VA develops it under 3.310 rather than as a new direct claim. Attach the nexus opinion and the medical records, or upload them after filing. File online, by mail to the Claims Intake Center (PO Box 4444, Janesville, WI 53547-4444), in person or through a free accredited representative. If VA previously denied the condition, a Supplemental Claim (VA Form 20-0995) with the new nexus opinion reopens it. VA will usually schedule a claim exam; bring your medication list and tell the examiner how the primary condition affects the secondary one.
Reference: https://www.va.gov/disability/file-disability-claim-form-21-526ez/
Step 5: Understand how the new rating combines
Ratings are combined, not added (38 CFR 4.25): VA applies each rating to the remaining "efficiency". A 70% rating plus a 10% rating gives 73, rounded to 70%; 70% plus 30% gives 79, rounded to 80%; disabilities of paired limbs or organs get a bilateral factor (38 CFR 4.26). Crossing a threshold can matter more than the percentage: 30% adds dependent allowances, and the move from 90% to 100% raises the single-veteran rate from $2,362.30 to $3,938.58 a month and, if permanent and total, opens CHAMPVA and Chapter 35 education for your family. Separately rated secondary conditions also count toward the 60%/70% thresholds for TDIU.
Critical tips
- Common examples VA sees: radiculopathy or hip and back problems secondary to a service-connected knee or ankle; depression secondary to chronic pain; erectile dysfunction secondary to diabetes, prostate treatment or medications; sleep apnea or GERD claims tied to service-connected conditions or their medications — each still needs the nexus opinion.
- The VA home loan funding fee is already waived for a veteran receiving compensation for any service-connected disability; it is not a 100% threshold.
- If the primary condition is presumptive (Agent Orange, PACT Act), a secondary condition is still claimed the same way — the presumption covers the primary, the nexus opinion covers the link.
- For survivors: DIC is payable when a secondary service-connected condition caused or contributed to the death.
- A county veterans service officer can file the claim for free and pull your claims file: warriorsfund.org/find-cvso.
- In crisis: dial 988 then press 1, or text 838255.