How do I prove secondary service connection when the VA agrees I have the condition but denies it's connected to my service-connected disability?

Secondary service connection is governed by 38 CFR 3.310, which allows compensation for a condition that is either caused or aggravated by an already service-connected disability. The key legal standard is "at least as likely as not" (a 50% or greater probability), not certainty. Denials often happen not because the medical facts are wrong, but because the nexus evidence in the file doesn't explicitly use that language or doesn't directly address aggravation as opposed to causation.

For conditions like vertigo tied to tinnitus, or hypertension that fluctuates with tinnitus/vertigo flare-ups, the file needs a medical opinion — from a VA C&P examiner or a private physician — that specifically states the secondary condition is at least as likely as not caused OR aggravated by the service-connected condition, and ideally explains the physiological mechanism. A diary showing correlation is useful lay evidence, but it rarely substitutes for a clinician connecting the dots in writing. If a C&P exam confirms a diagnosis but the examiner's opinion is silent on aggravation or uses vague language, that's often the actual basis for denial, not the underlying facts.

What would this rating pay you? (2026 rates)

Official 2026 VA monthly compensation, including the 2.8% COLA increase.

Rating Married Children

per month · per year, tax-free

Dependent add-ons start at a 30% rating. Child-only and dependent-parent rates: see the full 2026 pay chart.

2026 base rates, all ratings (veteran alone)

Rating	Monthly (2026, incl. 2.8% COLA)
10%	$180.42
20%	$356.66
30%	$552.47
40%	$795.84
50%	$1,132.90
60%	$1,435.02
70%	$1,808.45
80%	$2,102.15
90%	$2,362.30
100%	$3,938.58

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When a decision is wrong on the medical evidence, the main avenues are a Higher-Level Review (VA Form 20-0996, no new evidence, just asks a senior reviewer to re-examine the existing record for error), a Supplemental Claim (VA Form 20-0995, allows new and relevant evidence, such as an updated private nexus letter specifically addressing aggravation), or a Notice of Disagreement to the Board of Veterans' Appeals (VA Form 10182). Many veterans find that a tightly worded new nexus opinion filed as a Supplemental Claim resolves the exact defect that caused the prior denial.

The concrete next step is to obtain a new, explicit nexus letter from a treating or private physician that uses the "at least as likely as not" standard and directly addresses aggravation, then file it as a Supplemental Claim (VA Form 20-0995) with that evidence attached.