Secondary Service Connection: When One Service-Connected Condition Causes or Worsens Another

The basic compensation statutes, 38 U.S.C. § 1110 (wartime service) and 38 U.S.C. § 1131 (peacetime service), pay compensation for disability resulting from injury or disease incurred or aggravated in service.

VA's regulation on secondary conditions is 38 C.F.R. § 3.310 (alternate text). It recognizes two different theories:

• Causation (§ 3.310(a)). A disability that is "proximately due to or the result of" a service-connected disease or injury is itself service connected. Once granted, VA treats the secondary condition as part of the original one for service-connection purposes.
• Aggravation (§ 3.310(b)). If a service-connected condition makes a non-service-connected condition worse, beyond its natural progress, VA compensates the degree of worsening.

The aggravation rule comes from the Court of Veterans Appeals' en banc decision in Allen v. Brown, 7 Vet. App. 439 (1995). VA amended § 3.310 in 2006 to add paragraph (b) and explained in the Federal Register notice (71 Fed. Reg. 52,744) that the change was meant to conform its rules to Allen.

Section 3.310 also has two special rules. Under § 3.310(c), ischemic heart disease or other cardiovascular disease that develops after a service-connected amputation of one leg at or above the knee, or both legs at or above the ankles, is treated as resulting from the amputation. Under § 3.310(d), certain conditions, such as some cases of Parkinsonism, unprovoked seizures, certain dementias, depression, and some hormone deficiency diseases, are presumed to be caused by a service-connected traumatic brain injury when severity and timing requirements are met. Conditions that fall outside those requirements can still be considered under the general rules.

These two theories are separate, and a decision that addresses only one may leave the other unanswered. A medical opinion that says a condition was "not caused by" a service-connected disability does not, on its face, say whether the service-connected disability made it worse. When you read a denial or a C&P opinion, check whether both questions were addressed.

Aggravation claims have an extra requirement. Under § 3.310(b), VA will not find aggravation unless the baseline severity of the non-service-connected condition is shown by medical evidence. That evidence can be created before the aggravation began, or it can be the earliest medical evidence created after aggravation began and before VA received evidence of current severity. VA then rates the current level, subtracts the baseline, and subtracts any worsening due to natural progress. Only the remaining increase is compensated. The 2006 Federal Register notice states that the Veteran bears responsibility for establishing that baseline in these claims, which is why older treatment records can matter.

In practice, a secondary claim usually turns on three pieces of evidence:

• A current diagnosis (or persistent or recurrent symptoms) of the secondary condition.
• An existing service-connected disability.
• Evidence linking the two, through causation, aggravation, or both. This link is usually a medical question.

VA has a duty to help. Under 38 C.F.R. § 3.159(c)(4), VA provides a medical examination or opinion when the record lacks enough competent medical evidence to decide the claim and there is evidence of a current disability, a qualifying in-service event or presumption, and an indication that the claimed disability "may be associated with" the in-service event "or with another service-connected disability." That last phrase expressly covers secondary claims.

When the positive and negative evidence is roughly balanced, VA's reasonable-doubt rule in 38 C.F.R. § 3.102 requires VA to resolve the doubt in the Veteran's favor.

Secondary service connection is not a way to be paid twice for the same symptoms. VA's anti-pyramiding rule, 38 C.F.R. § 4.14, bars rating the same disability or the same manifestation under different diagnoses. A secondary condition is rated on its own symptoms, not on symptoms already counted in the primary rating.

Also, aggravation claims compensate only the measurable increase beyond baseline and natural progress, so the resulting rating may be lower than a rating for the full condition.

If VA denied a secondary claim, or decided a claim without considering a secondary theory that the record raised, these questions can help you review the decision:

• Did the decision and medical opinion address both causation and aggravation?
• Did the examiner give reasons for the conclusion, or only a bare "less likely than not"?
• Did VA consider the private records, medical literature, or lay statements you submitted?
• For aggravation, is there medical evidence of the condition's baseline severity, and did VA identify it?
• Is the denial based on the absence of evidence you could now obtain, such as a medical opinion that addresses the missing link?

Your answers can help you choose a review option. Our guides on choosing a VA review lane and new and relevant evidence explain how a Higher-Level Review, Supplemental Claim, or Board appeal fits different kinds of problems. If a secondary condition was never claimed, it can be filed as a new claim. VA's How to file a VA disability claim page lists "secondary claims" as a claim type and explains filing methods and the kinds of supporting evidence VA reviews.

Every claim depends on its own medical facts, and no particular result is assured. Understanding the two theories in § 3.310, and the baseline rule for aggravation, can help you see what a decision actually decided and what may still be missing.

This article is general information, not legal advice about any specific claim. Rules have exceptions, and every claim depends on its own facts and evidence.