Veterans plateau at 50–80% every day, never learning that the symptoms they live with may be secondary to conditions they already have rated. Law firms charge for this map. Here it is free.
A VA secondary condition is a disability caused or aggravated by a condition you already have service-connected — and under 38 CFR 3.310 it pays exactly like a direct one. PTSD commonly leads to sleep apnea, GERD, and medication-related sexual dysfunction; a rated back condition leads to radiculopathy and depression secondary to chronic pain; diabetes leads to peripheral neuropathy in each limb; long-term NSAIDs for a rated joint lead to GERD and gastritis. Each granted chain can move a combined rating 10–30 points, and the jump from 70% to 100% is worth roughly $2,000 more per month, tax-free, for life. This free tool maps your rated conditions to the secondaries most commonly connected to them, shows the 38 CFR rating each typically receives, builds a prioritized claim plan with the evidence each one needs, and walks you through the Intent to File that locks your effective date. One rule governs everything: it only surfaces conditions you actually live with — honest claims get granted.
“I have no in-service records for it.”
You don't need any. A secondary condition is service-connected through the condition you already have rated — that's the whole point of 38 CFR 3.310. Your service treatment records never need to mention it. The evidence is a current diagnosis plus a medical nexus opinion, both from today's doctors, not from your time in uniform.
“Nobody told me these chains exist.”
The map of what commonly flows from what is real, medical, and public — but it mostly lives behind law-firm intake funnels that charge a percentage of your back pay for it. That's the map on this page, free.
“That's just getting older.”
Sleep apnea after years of PTSD, a worn-out opposite knee, numbness running down a leg with a rated back — symptoms veterans write off as age or life are often medically downstream of a condition the VA already agreed was service-connected.
Browse the causation chains for any condition — including ones you don't have rated. Deep-curated chains cover the 26 highest-volume primaries; every other rated condition falls back to the CFR dataset's cross-references.
The tool runs on a curated causation graph built over the same CFR-verified, 200-condition dataset that powers our VA Combined Rating Calculator — one source of truth, so a 38 CFR amendment fixed there flows through here. The 26 highest-volume primary conditions (PTSD/mental health, TBI, back, neck, knees, feet, ankles, hips, shoulders, tinnitus, hearing loss, migraines, sleep apnea, hypertension, diabetes, GERD, IBS, asthma, sinus conditions, arthritis, fibromyalgia, Gulf War illness) carry deep, hand-curated chains: each edge states the plain-English medical mechanism, a qualitative commonality tier, the evidence that moves the claim, and the rating band the secondary typically receives when granted. Every other rated condition falls back to the dataset's own commonly-filed cross-references. We use qualitative tiers — "very commonly granted," "commonly granted," "needs strong nexus evidence" — instead of invented percentages, and cite real statistics only where a public source exists.
Rating projections combine your entered conditions with each candidate's typical outcome using the VA's actual combination math (38 CFR 4.25: whole-person combination, final value rounded to the nearest 10). Dollar figures use the 2026 VA compensation tables (effective December 1, 2025) with your dependent configuration. Two deliberate conservatisms: the bilateral factor (38 CFR 4.26) is not added to projections — the tool doesn't ask which side each condition is on, so paired-limb grants would pay slightly more than shown — and mental-health chains never project a second rating, because the VA assigns one rating for all mental disorders combined (38 CFR 4.130); when you already have a rated mental health condition, those chains are presented as evidence for an increase instead. Erectile dysfunction and FSAD are modeled at their real outcome: 0% plus SMC-K, a separate $139.87/month payment.
The Intent-to-File module reflects 38 CFR 3.155: an ITF (VA Form 21-0966, online, or by phone) locks your potential effective date for 12 months while you gather evidence, and granted claims pay back to the ITF date. The projections here are educational estimates, not a promise of any outcome — the C&P exam and the rating decision set the real numbers. This tool never coaches exaggeration: it exists to connect symptoms you already live with to the service-connected conditions that may be causing them, and to route you to free help (an accredited VSO) rather than percentage-fee claim companies.
A secondary condition is a disability caused or aggravated by a condition you already have service-connected, rather than by service directly. Under 38 CFR 3.310, it is compensated exactly like a direct service-connected condition once granted. Classic examples: radiculopathy (nerve pain down the leg) secondary to a rated back condition, sleep apnea secondary to PTSD, depression secondary to chronic pain, and peripheral neuropathy secondary to diabetes. The three elements of a secondary claim are (1) a current diagnosis, (2) an already service-connected primary condition, and (3) a medical nexus opinion connecting the two.
The most commonly claimed secondaries to PTSD and other rated mental health conditions are sleep apnea (disrupted sleep architecture plus medication-related weight gain), GERD (stress-driven acid production and medication side effects), IBS (the gut-brain axis), migraines, hypertension, and erectile dysfunction or female sexual arousal disorder as a side effect of SSRI/SNRI medications — the last of which is rated 0% but unlocks SMC-K, a separate $139.87 monthly payment most veterans never claim. Every one of these requires that you actually have the condition, a diagnosis, and a medical nexus opinion.
An Intent to File (VA Form 21-0966, or simply starting a claim on VA.gov or calling 800-827-1000) locks today's date as your potential effective date and gives you 12 months to gather evidence and submit the actual claim. If the claim is granted, back pay runs from the intent-to-file date — not from the day you finally submitted. It is free, takes minutes, and does not obligate you to file. If you believe you have a valid secondary claim but need time for a diagnosis or nexus letter, submitting an Intent to File today is the single highest-value step you can take: every month of evidence-gathering it covers is a month of back pay protected.
In most cases, yes — the nexus opinion is the heart of a secondary claim. It is a medical professional's written statement that your secondary condition is "at least as likely as not" caused or aggravated by your service-connected primary condition, with a rationale. Some chains are so well established (radiculopathy on a back claim's own exam findings, or presumptive Gulf War conditions under 38 CFR 3.317) that a separate letter may not be needed, but for chains like PTSD to sleep apnea or diabetes to neuropathy, a clear nexus opinion from a treating physician or qualified examiner is what separates granted claims from denied ones.
No — and this is the misconception that stops more secondary claims than any other. A secondary condition is service-connected through the condition you already have rated, under 38 CFR 3.310. Your service treatment records never need to mention it, and it doesn't matter if it started years after you left the military. The evidence a secondary claim needs is entirely from the present: a current diagnosis of the secondary condition, your existing service-connected rating on the primary, and a medical nexus opinion connecting the two. If sleep apnea developed a decade after service in a veteran rated for PTSD, the absence of sleep apnea in the service records is irrelevant — the claim runs through the PTSD.
The most commonly granted secondary claims include: radiculopathy secondary to a rated back or neck condition (rated per limb), depression or anxiety secondary to chronic pain, peripheral neuropathy secondary to diabetes (rated per extremity), erectile dysfunction secondary to medications or diabetes (0% plus SMC-K), migraines secondary to TBI, tinnitus secondary to TBI or alongside rated hearing loss, sleep apnea secondary to PTSD, hypertension secondary to sleep apnea or diabetes, and GERD or gastritis secondary to long-term NSAID use for a rated pain condition. Each claim still requires a real diagnosis and a medical nexus — commonality is not a guarantee.