To file a secondary VA claim, submit VA Form 21-526EZ identifying the new condition and marking it as secondary to a disability you’re already service-connected for, and back it with a medical opinion linking the two at “at least as likely as not.” The form is the same one used for any disability compensation claim; what makes a secondary claim different is the evidence you attach to it and the theory of connection you’re arguing.
Before you file, it helps to know which of the two secondary theories fits your situation, because they take different evidence.
The Two Ways a Secondary Condition Qualifies
Federal regulation recognizes two paths to secondary service connection: direct causation and aggravation.1eCFR. 38 CFR 3.310 – Disabilities That Are Proximately Due to, or Aggravated by, Service-Connected Disease or Injury
Direct causation means your service-connected condition produced the new one. A veteran with a service-connected knee injury who develops chronic back problems from an altered gait is a textbook case. When the VA grants service connection on this theory, the secondary condition is treated as part of the original disability for rating purposes.
Aggravation is different. You have a condition that isn’t itself service-connected, but a service-connected disability made it worse beyond its natural progression. The VA will service-connect only the increase in severity, not the whole condition, and it needs medical evidence of your baseline severity before the worsening began. Compensation covers the difference between that baseline and where you are now.
The aggravation path is harder to win. If you have no records showing what the condition looked like before the worsening started, the VA falls back on the earliest records it can find between onset and current diagnosis. Claims fall apart here often, because veterans who didn’t see a doctor until things were bad have little to establish the baseline with.
Evidence That Decides the Claim
You need to show three things: a current diagnosis of the secondary condition, an existing service-connected disability, and a medical link between them. The link is what most claims turn on.
The Nexus Letter
A nexus letter is a written opinion from a qualified healthcare provider stating that your secondary condition is connected to your service-connected disability. The VA is looking for a specific phrase and standard: the opinion should say the connection is “at least as likely as not,” meaning at least a 50 percent probability. Weaker language usually won’t carry the claim.2Veterans Affairs. Evidence Needed for Your Disability Claim
A strong letter does more than state that conclusion. It walks through your medical history, identifies the mechanism connecting the two conditions, and explains why the connection isn’t coincidental. If you’re claiming aggravation, the letter should address your baseline severity before the worsening began. The provider’s credentials matter too: a podiatrist writing about a cardiac condition raises a credibility problem the VA will notice.
Medical Records and Lay Statements
Gather every record documenting the secondary condition: doctor’s reports, imaging, lab work, treatment notes from both VA and private providers. Records that show how the condition developed over time are especially useful because they help establish the timeline between the primary and secondary disabilities.2Veterans Affairs. Evidence Needed for Your Disability Claim
Lay evidence helps around the edges. You can submit a personal statement describing when symptoms started and how they’ve progressed. Statements from family, friends, or fellow service members go on VA Form 21-10210. Lay evidence doesn’t replace medical documentation, but it fills gaps and adds context that clinical notes miss.
Filing the Claim
Use VA Form 21-526EZ. On the form, identify the condition you’re claiming and indicate that it’s secondary to a specific disability you’re already service-connected for.3Veterans Affairs. File for Disability Compensation With VA Form 21-526EZ
You can submit three ways:
- Online through VA.gov. Starting the application online automatically creates an intent to file, which locks in a potential effective date.
- By mail to the VA Evidence Intake Center.
- In person at a VA Regional Office.
Accredited representatives at Veterans Service Organizations like the VFW, DAV, and American Legion will help you prepare and submit at no cost. That help is worth considering when your claim relies on an aggravation theory or a longer medical chain, because these representatives know what the VA looks for and can flag problems before submission.
File an Intent to File First
Your effective date, which determines when compensation starts, is the later of the date the VA received your claim or the date the secondary condition first arose.4Veterans Affairs. Disability Compensation Effective Dates
Submitting VA Form 21-0966, or starting an online application (which creates an automatic intent to file), sets a potential effective date right away. You then have one year to submit the full claim, and any benefits awarded date back to the intent-to-file date rather than the date you filed the completed application.5Veterans Affairs. Your Intent to File a VA Claim
If it takes you eight months to get a nexus letter and gather records, an intent to file protects eight months of back pay. Skip it and that money is gone.
The Fully Developed Claims Program
If you submit all supporting evidence upfront, certify no additional evidence exists, and agree to attend any scheduled exams, your claim qualifies as a Fully Developed Claim and is processed faster. If you later find additional evidence and submit it, the VA pulls the claim out of the FDC track and processes it on the standard timeline.6Veterans Affairs. Fully Developed Claims Program
For secondary claims, the FDC path works when your nexus letter, medical records, and any lay statements are already assembled before you file.
After You File
The VA acknowledges your claim after submission. Online filings show confirmation immediately; paper submissions get a response letter roughly a week after receipt.7Veterans Affairs. The VA Claim Process After You File Your Claim
The C&P Exam
The VA may schedule a Compensation and Pension exam. It isn’t a treatment appointment. The examiner won’t prescribe medication or refer you for care. Their job is to document severity and, in many cases, offer an opinion on whether your secondary condition is connected to your service-connected disability.8Veterans Affairs. VA Claim Exam (C&P Exam)
Arrive 15 minutes early. Wear clothes that let you move if a physical exam is involved. If you have recent non-VA records, submit them before the appointment rather than handing them to the examiner. The examiner may perform a physical exam, work through a Disability Benefits Questionnaire specific to your condition, and order tests like X-rays or bloodwork at no cost.
Be honest and thorough. Describe your worst days, not just how you feel that morning. If asked about limitations, don’t minimize them out of habit. This exam shapes the rating decision directly.
How Long It Takes
As of February 2026, the VA reports an average of about 76.6 days to complete disability-related claims. Complex claims with multiple conditions take longer. FDC filings move faster when the evidence is complete at submission.7Veterans Affairs. The VA Claim Process After You File Your Claim
How a Secondary Rating Changes Your Payment
When the VA grants secondary service connection, the new condition gets its own disability rating, which is then combined with your existing rating using what veterans call VA math.9Veterans Affairs. About Disability Ratings
It isn’t ordinary addition. The VA uses a whole-person method: each successive rating applies only to your remaining efficiency. If you have a 50 percent rating, the VA considers you 50 percent efficient. A second condition rated at 30 percent takes 30 percent of that remaining 50 percent (15 percent), which brings the raw combined rating to 65 percent. That gets rounded to the nearest 10, so 70 percent.10eCFR. 38 CFR 4.25 – Combined Ratings Table
Each additional rating has diminishing returns. Understanding the math sets realistic expectations for how a secondary claim will move your combined rating.
If your secondary conditions affect both sides of the body (both knees, both legs, both arms), the VA applies a 10 percent bilateral factor. Paired ratings are combined first, then 10 percent of that combined value is added before other combinations. It’s a small bump, but it can push a combined rating past a rounding threshold.11eCFR. 38 CFR 4.26 – Bilateral Factor
One threshold worth knowing: veterans rated at 30 percent or higher receive additional compensation for dependents. A secondary claim that pushes a combined rating from 20 to 30 percent unlocks a separate category of dependent benefits on top of the higher base payment.12Veterans Affairs. Current Veterans Disability Compensation Rates
If the VA Denies the Claim
A denial isn’t the end. Under the Appeals Modernization Act, you have three review options:13Veterans Benefits Administration. Appeals Modernization
- Supplemental Claim. Submit new and relevant evidence the VA didn’t have before. This is usually the right move when the original claim lacked a strong nexus letter or was missing medical records.
- Higher-Level Review. A senior reviewer takes a fresh look at the same evidence. You can’t add new evidence, but you can request an informal conference to point out errors. If the reviewer finds the VA failed to obtain evidence it should have, the claim gets reopened.
- Board Appeal. Your case goes to a Veterans Law Judge. You can choose direct review (no new evidence, no hearing), evidence submission (new evidence, no hearing), or a hearing where you testify and can submit additional evidence within 90 days afterward.
The most common reason secondary claims fail is a weak or missing nexus letter. If the denial letter says the evidence doesn’t show a connection between your conditions, getting a stronger nexus letter from a specialist and filing a Supplemental Claim is usually the most direct fix. Read the denial letter carefully; it tells you exactly which element the VA found lacking, and that’s where the next round should focus.14Veterans Affairs. Choosing a Decision Review Option