Your Rated Disability Can Cause a Second One Veterans Affairs Also Has to Pay For

6 min read · Last updated August 22, 2026

In this article

• What secondary service connection is
• Causation versus aggravation
• Conditions VA already presumes are secondary
• How to file
• What weakens a secondary claim
• Frequently asked questions

James Okafor, a veteran already rated for a service-connected traumatic brain injury (TBI) from an in-service blast exposure, developed unprovoked seizures four years later. He assumed the seizures were a separate medical problem with no connection to his existing VA rating. Under federal regulation, a seizure disorder that appears after a moderate or severe service-connected TBI can be presumed connected to that TBI without Okafor having to prove the link from scratch.

What secondary service connection is

Federal regulation 38 CFR § 3.310 states that a disability proximately due to, or the result of, a service-connected disease or injury is itself considered service connected. Once that link is established, the regulation treats the new, secondary condition as part of the original condition for compensation purposes, not as an unrelated claim starting from zero.

This matters because a veteran’s original rated condition often is not the last word on their health. A service-connected joint injury can change how someone walks or moves for years, and that change can create real, ratable damage somewhere else in the body over time.

Causation versus aggravation

There are two distinct paths to a secondary connection, and they work differently. Under the causation path, the service-connected condition directly caused the new condition. Under the aggravation path, a condition that already existed and was not service connected got permanently worse because of a service-connected condition.

The regulation is specific about how that math works. VA will not concede aggravation unless the baseline severity of the pre-existing condition is established with medical evidence from before the aggravation began, or the earliest available evidence closest to that point. From there, the rating activity determines the baseline severity and the current severity under VA’s Schedule for Rating Disabilities, and rates only the difference, after also subtracting any decline that would have happened anyway from the natural progress of the disease. A pre-existing condition that would have worsened on its own regardless of service does not get credited to the veteran twice.

Conditions VA already presumes are secondary

Two categories are written directly into the regulation as automatic presumptions, meaning a veteran does not have to independently prove the medical link in these specific situations. A veteran with a service-connected amputation of one leg at or above the knee, or both legs at or above the ankles, is presumed to have any resulting ischemic heart disease or other cardiovascular disease connected to that amputation. A veteran with a service-connected moderate or severe TBI is presumed, absent clear evidence otherwise, to have several conditions connected to it if they appear within set windows: Parkinsonism or Parkinson’s disease at any point after a moderate or severe TBI, unprovoked seizures after a moderate or severe TBI, certain dementias if they show up within 15 years of a moderate or severe TBI, and depression if it shows up within 3 years of a moderate or severe TBI or within 12 months of a mild TBI.

Outside of these written presumptions, a secondary connection still requires the causation or aggravation showing described above, generally supported by a medical opinion connecting the two conditions.

How to file

A secondary condition is filed the same way an original disability claim is filed, on VA Form 21-526EZ, the Application for Disability Compensation and Related Compensation Benefits. It is treated as a new claim for that condition, not a Supplemental Claim. A Supplemental Claim exists specifically to reopen a previously decided issue with new evidence, or to request review under a newly presumptive condition; VA’s own guidance is direct that a condition which has simply gotten worse needs a claim for increased compensation, not a Supplemental Claim, and the same logic applies to a genuinely new secondary condition.

Any doubt in the evidence works in the veteran’s favor under VA’s standard practice: when the evidence for and against a claim is roughly balanced, that reasonable doubt is resolved in favor of the veteran, rather than requiring the veteran to prove the connection beyond any question.

What weakens a secondary claim

The aggravation path fails most often when there is no medical evidence establishing what the pre-existing condition looked like before the alleged aggravation began. Without that baseline, VA has no starting point to measure an increase in severity against, and the claim cannot proceed on the aggravation theory at all. A causation claim without a medical opinion connecting the two conditions faces the same problem from a different angle: there is no evidence tying the two conditions together at all. A gap in continuity of treatment between the original condition and the appearance of the secondary one can also weaken a claim, since it gives VA less to work with when tracing the connection.

Frequently asked questions

What is the difference between a causation claim and an aggravation claim? A causation claim argues your service-connected condition directly caused a new condition. An aggravation claim argues a condition you already had, unrelated to service, got permanently worse because of a service-connected condition. VA only compensates the portion of decline the service-connected condition actually caused under the aggravation path.

Does VA automatically connect any condition to my service-connected disability? Only in specific, written situations. A service-connected TBI carries automatic presumptions for conditions like Parkinsonism, unprovoked seizures, certain dementias, and depression within set time windows. A service-connected major amputation carries an automatic presumption for resulting cardiovascular disease. Outside those categories, you generally need medical evidence connecting the two conditions.

Do I need a doctor’s opinion to file a secondary claim? Generally yes, unless your situation falls under one of VA’s automatic presumptions. A medical opinion connecting the new or worsened condition to your service-connected disability is what establishes the link VA needs to grant a secondary claim.

Should I file a secondary claim as a Supplemental Claim? No. A Supplemental Claim is for reopening a previously decided issue with new evidence, not for a genuinely new secondary condition. File a new secondary condition the same way you filed your original claim, on VA Form 21-526EZ.

What happens if my pre-existing condition would have gotten worse anyway, without my service-connected disability? VA subtracts that natural decline from the total increase in severity before rating the aggravation. Only the portion of the worsening actually caused by your service-connected disability gets compensated, not decline that would have happened regardless.