Nearly 60 percent of veterans receiving VA disability compensation carry a musculoskeletal condition, and paired joints — two knees, two feet, two shoulders — sit near the top of that list. Yet many of those veterans never see the bilateral factor applied to their combined rating. The pain point is blunt: a veteran with two rated knees can sit at 50 percent when the same evidence, run correctly through 38 CFR 4.26, lands at 60 percent. At 2026 rates that gap is roughly $302 a month. This guide explains what the VA bilateral factor is, who qualifies, how the math runs, and how to check whether a rating decision actually applied it.
Key Takeaways
- Confirm that both sides of a pair carry a compensable rating — the bilateral factor never applies to a single limb.
- Combine the paired ratings first, then add 10 percent of that combined value before any further combining.
- Document the non-dominant or “weaker” side just as hard as the side that hurts most, because a 0 percent rating kills the factor.
- Read the code sheet, not the narrative, to verify the factor was applied.
- Challenge a missing bilateral factor as a calculation error, not as a new claim for a new condition.
- Recheck the math whenever a new rating is added, because ordering changes the result.
Table of Contents
- Who Qualifies for the VA Bilateral Factor
- Evidence That Puts Both Sides on the Record
- How the Bilateral Factor Math Actually Works
- Five Steps to Get the Bilateral Factor Applied
- After the Decision: Verifying, Correcting, and Appealing
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Who Qualifies for the VA Bilateral Factor
The bilateral factor is not a benefit a veteran applies for. It is a calculation rule that VA is required to run whenever the ratings on file meet the conditions in 38 CFR 4.26. The regulation states that the factor “is not applicable unless there is partial disability of compensable degree in each of 2 paired extremities, or paired skeletal muscles.” Two words in that sentence carry the weight: partial and compensable.
Partial means the extremity is rated at less than total. Compensable means the rating is 10 percent or higher. A veteran with a 20 percent right knee and a 0 percent left knee has nothing to combine — the factor sits idle until the left side reaches 10 percent. This is where a large number of veterans lose money quietly. The weaker side gets mentioned in passing at the C&P exam, receives a non-compensable rating, and the paired bonus never triggers.
The conditions on each side do not have to match. A veteran can carry degenerative arthritis in one knee and a meniscal tear in the other and still meet the rule, because the regulation looks at the paired extremities, not the paired diagnoses. Context matters here: with more than 6.3 million veterans receiving VA disability compensation according to the VBA Annual Benefits Report, paired-joint claims are routine work for rating staff — and routine work is where calculation slips happen.
Which Body Pairings Count
The regulation covers both arms, both legs, and paired skeletal muscles. In practice, that includes both knees, both ankles, both feet, both hips, both shoulders, both elbows, both wrists, and both hands. It also covers a mixed pair — one upper extremity and one lower extremity — when both are rated at a compensable level. What it does not cover are conditions of the spine, the torso, or any single midline structure, because those are not paired extremities. Veterans should confirm current criteria on VA.gov before assuming a specific joint qualifies.
Evidence That Puts Both Sides on the Record
The bilateral factor lives or dies on whether the second side is documented as a rated disability. Tinnitus alone accounts for more than 3.5 million veterans on the compensation rolls, which shows how thoroughly VA records single, well-documented conditions — and how easily a second knee or second ankle gets treated as an aside instead of a claim.
The starting point is the service treatment record. In-service complaints about the “other” side are often buried in sick call notes, profiles, or a single line in a separation physical. Requesting the complete file and reading it page by page frequently surfaces the second-side entry a veteran forgot existed. Private treatment records fill the gap after separation: orthopedic notes, imaging reports, physical therapy records, and pharmacy histories all establish that the condition continued and worsened.
Service Records, Private Files, and Imaging
Range-of-motion measurements matter more than pain narratives for paired joints, because the rating criteria for the musculoskeletal system are largely motion-based. X-ray or MRI findings that show arthritic change on both sides carry significant weight. Where private treatment exists, a Disability Benefits Questionnaire completed by the treating provider can put both sides in the same evidentiary format VA examiners use.
Lay Statements and Toxic-Exposure Pathways
Lay evidence is admissible for what a veteran and those around them can observe — swelling, limping, giving way, an inability to stand a full shift. A spouse or former squad member describing both knees failing on a specific deployment can bridge a gap where records are thin. Separately, veterans whose paired-extremity problems trace to conditions recognized under the PACT Act — or to a presumptive condition that produced secondary joint damage — should develop that pathway too. Presumptive service connection can establish the underlying disease; the paired joint ratings then feed the bilateral calculation. Consistency is what persuades: every statement, treatment note, and questionnaire should describe the same left-and-right pattern, in the same terms, across the same time period.
How the Bilateral Factor Math Actually Works
VA does not simply add ratings. Under 38 CFR 4.25, ratings combine against remaining efficiency, then round to the nearest 10 at the end. The bilateral factor inserts one extra move into that sequence. The regulation directs that the right and left side ratings be combined as usual, and then “10 percent of this value will be added (i.e., not combined) before proceeding with further combinations.” That word — added, not combined — is the entire mechanic.
The result is then treated as a single disability for the purpose of arranging remaining disabilities in order of severity and for all further combinations. Because rounding happens only at the end, a few extra points can move a veteran across a rating band. With the 2.8 percent cost-of-living adjustment effective December 1, 2025, the 2026 monthly rate for a veteran alone at 50 percent is $1,132.90 and at 60 percent is $1,435.02 — so a single band crossing is worth roughly $302 a month before dependents are added.
A Two-Knee Example, Step by Step
Assume a 30 percent right knee and a 30 percent left knee. Combining under 4.25 gives 51 — 30, plus 30 percent of the remaining 70. Standing alone, 51 rounds down to a 50 percent combined rating. Now apply the bilateral factor: 10 percent of 51 is 5.1, added rather than combined, for 56.1. That value rounds to 60 percent. Same two ratings, same evidence, one regulation correctly applied, and the veteran moves a full band.
When All Four Extremities Are Involved
Where both arms and both legs are rated, the regulation directs combining all four in the order of their individual severity, then adding 10 percent of that combined value. It is one bilateral calculation across the four extremities, not two separate 10 percent additions. Getting the ordering wrong is a common source of understated combined ratings.
Five Steps to Get the Bilateral Factor Applied
The bilateral factor is applied automatically when the ratings support it, so the veteran’s job is to make sure the ratings support it. These five steps work in order.
- Inventory both sides. List every paired joint with any history of injury, surgery, or chronic pain, and note which side already carries a rating and which does not.
- File a claim for the unrated side. Use VA Form 21-526EZ for a new condition, or a claim for increase if the second side sits at 0 percent. File an Intent to File first to protect the effective date.
- Attach side-specific evidence. Every record should name left or right explicitly. Ambiguous documentation is the single most common reason a second-side claim stalls.
- Prepare for the examination on both sides. The examiner will measure each joint separately; describing symptoms on the worst day rather than the best day applies to each side individually.
- Verify the calculation once the decision arrives. Do not assume. Confirm the factor on the code sheet, which is discussed below.
Choosing Between a New Claim and an Increase
If the second side has never been rated, it is a new claim for service connection. If it carries a 0 percent rating, it is a claim for increase, and the medical question is whether the current level of impairment now meets compensable criteria. The distinction matters because it determines the form, the evidence emphasis, and how the effective date is set. Veterans should confirm current form requirements on VA.gov, since form numbers and submission channels change.
Sequencing Multiple Paired Claims
When several pairs are in play — knees and ankles, or shoulders and wrists — filing them together lets the rating activity run one complete calculation instead of a series of partial ones. Piecemeal filing produces a chain of amended decisions, and each recalculation is another chance for the ordering rule to be applied inconsistently.
After the Decision: Verifying, Correcting, and Appealing
A rating decision arrives with a narrative explanation and a code sheet. The narrative rarely explains the arithmetic. The code sheet is where the bilateral factor shows up, typically as a separate line reflecting the added value alongside the combined evaluation. Reading the code sheet is the only reliable way to confirm the factor was applied — and requesting the claims file provides the full record if the code sheet is unclear.
The Exception That Protects Veterans
Effective December 27, 2023, VA amended 38 CFR 4.26 to add an exception. Because bilateral disabilities are treated as one disability for ordering purposes, there are combinations where including a paired disability in the bilateral calculation produces a lower combined evaluation than leaving it out. The amended regulation directs that in those cases, the affected bilateral disabilities are removed from the bilateral calculation and combined separately, so the veteran receives the most favorable combined evaluation. VA described the change as a liberalizing issue. Veterans whose combined rating looks mathematically odd across several paired conditions should ask whether this exception was considered.
Correcting a Missing Bilateral Factor
A missing bilateral factor is a calculation problem, not a new medical question, which shapes the correct response. A Higher-Level Review asks a senior reviewer to look at the same evidence and identify the error — often the right fit when the ratings themselves are not in dispute. A Supplemental Claim fits better when new evidence is needed to make the second side compensable. Where the error appears in a decision that became final, veterans sometimes raise a clear and unmistakable error argument, though that standard is demanding. Deadlines apply to each lane, and current appeal deadlines should be confirmed on VA.gov before choosing a path. A VA-accredited representative can review the code sheet arithmetic at no cost before a lane is selected.
Run the Free VA Claim Readiness Test
The bilateral factor rewards veterans who document both sides and then verify the arithmetic. Most do neither, and the rating reflects it. The free VA Claim Readiness Test at avoyvet.com walks through which paired conditions are already rated, which evidence gaps are keeping a second side non-compensable, and what to check on a rating decision before accepting it. AVOY Veteran Navigator AI™ can then answer follow-up questions on paired-joint evidence, combined ratings, and appeal lanes in plain language, drawing on the AVOY VA Benefits Mastery Library.
Frequently Asked Questions
Does the bilateral factor add 10 percentage points to a rating?
No, and this is the most common misunderstanding. The factor adds 10 percent of the combined value of the paired disabilities, not 10 percentage points. If two paired ratings combine to 51, the factor adds 5.1 — not 10. That produces 56.1, which rounds to 60 percent. Where the combined value is smaller, the addition is smaller and may not change the rounded rating at all. Two 10 percent ankles combine to 19; adding 1.9 gives 20.9, which still rounds to 20 percent. The factor helps most when the combined value sits just under a rounding threshold.
Do both sides need the same diagnosis?
No. The regulation applies to paired extremities, not paired diagnoses. A veteran can have degenerative arthritis in the right knee and instability from a torn ligament in the left knee and still qualify, as long as each side carries a compensable rating of 10 percent or more. The same holds for ankles, shoulders, hips, wrists, and hands. What matters is that the disability affects each member of a pair to a compensable degree, not that the two conditions share a diagnostic code, a common cause, or the same date of onset. Different codes on the left and right are ordinary.
Does a 0 percent rating on one side count?
No. The regulation requires partial disability of compensable degree in each of two paired extremities, and 0 percent is non-compensable. This is where the largest share of missed bilateral factors originates. A veteran who was rated 0 percent on the weaker side years ago may now have imaging, treatment records, and range-of-motion findings supporting a compensable level. Filing a claim for increase on that side can activate the factor across the pair. Reviewing old decisions for 0 percent entries on paired joints is one of the highest-value audits a veteran can run, and it costs nothing but reading time.
Can the bilateral factor apply to one arm and one leg?
Yes. The regulation contemplates a mixed pairing of one upper and one lower extremity when both are rated at a compensable level. This surprises many veterans who assume the factor requires two of the same limb. In practice, a compensable right shoulder and a compensable left knee can support the calculation. The ordering rules still apply, and the resulting value is treated as a single disability for further combinations. Because mixed pairings are less familiar to many veterans, they are worth verifying line by line on the code sheet of any rating decision that involves them.
Does the bilateral factor apply to spine or back conditions?
No. The spine is a single midline structure, not a paired extremity, so a back or neck rating does not qualify on its own. However, a spine condition frequently causes radiculopathy in both lower extremities or both upper extremities. Those radiculopathy ratings are ratings of paired extremities, and when each side is compensable, they can support the bilateral factor even though the spine rating itself cannot. Veterans with bilateral radiculopathy secondary to a spine condition should confirm that the factor was applied to the extremity ratings, since the spine rating drawing all the attention is exactly how the paired ratings get overlooked.
Is a separate application required?
No. There is no bilateral factor form and no bilateral factor claim. It is a calculation rule VA is required to apply whenever the ratings on file meet the criteria in 38 CFR 4.26. The practical work is upstream, making sure both sides are service connected and rated at a compensable level, and downstream, verifying on the code sheet that the calculation was performed. When it is missing, the remedy runs through the standard review lanes rather than through any application specific to the factor. Veterans should confirm current forms and review options on VA.gov, since submission channels change from year to year.
Can the bilateral factor ever lower a combined rating?
It could under the older version of the regulation, because bilateral disabilities are treated as one disability for ordering purposes, and that ordering occasionally produced a worse result. Effective December 27, 2023, VA amended 38 CFR 4.26 to add an exception: where including one or more bilateral disabilities in the calculation would yield a lower combined evaluation, those disabilities are removed from the bilateral calculation and combined separately, producing the most favorable result. VA characterized the amendment as liberalizing. Veterans with several paired conditions whose combined rating looks understated should ask whether the exception was applied.
Educational information only — not legal, medical, or claim representation, and not affiliated with the U.S. Department of Veterans Affairs. For help filing or appealing, contact a VA-accredited VSO (often free), claims agent, or attorney. For current rates, forms, and deadlines, see VA.gov.
