What is the VA bilateral factor?

Under 38 CFR 4.26, when a veteran has compensable service-connected disabilities affecting both arms, both legs, or paired skeletal muscles, the VA combines the left- and right-side ratings as usual, then adds 10 percent of that combined value before combining with the veteran's other disabilities. The result is treated as one disability for all further combinations.

Does the bilateral factor add 10 percentage points to my rating?

No. It adds 10 percent OF the combined value of the paired disabilities, not a flat 10 points. For example, a 30% right knee and 20% left knee combine to 44; the bilateral factor adds 4.4 (10% of 44), giving 48 after rounding to the nearest whole number.

Does an arm and a leg qualify for the bilateral factor?

No. The bilateral factor requires paired extremities — both arms or both legs (or paired skeletal muscles). One upper extremity plus one lower extremity does not qualify. However, the conditions do not have to match: a left knee condition and a right hip condition qualify because both affect the lower extremities.

Can the bilateral factor ever lower my combined rating?

Not anymore. Since April 14, 2023, 38 CFR 4.26(d) requires the VA to exclude one or more bilateral disabilities from the bilateral-factor calculation whenever including them would produce a lower combined evaluation. The VA must use whichever computation is most favorable to the veteran.

The VA Bilateral Factor Explained — 38 CFR § 4.26 With Worked Examples

June 29, 2026 · 6 min read

Quick answer: when you have compensable ratings on both arms or both legs, the VA combines those ratings first, then adds 10% of that combined value (not 10 percentage points) before combining with your other disabilities. Two knees at 30% and 20% combine to 44; the bilateral factor turns that into 48. It's automatic — and our 2026 VA Disability Calculator applies it for you.

The bilateral factor is one of the most misunderstood pieces of VA math. Veterans hear "the VA adds 10%" and expect a flat bump; raters apply something subtler. Here is exactly how 38 CFR § 4.26 works, with the arithmetic shown — including a 2023 rule change most older guides still miss.

What the bilateral factor is

When partial disability results from disease or injury of both arms, both legs, or paired skeletal muscles, the regulation directs the rater to combine the ratings for the right and left sides as usual under the combined ratings table (38 CFR § 4.25), and then add — not combine — 10 percent of that value. The result is then treated as one disability when it's ranked and combined with everything else you're rated for.

The logic: losing function on both sides of the body is more disabling than the two ratings suggest in isolation, so the schedule compensates for the pairing.

The math, step by step

Say you're rated 30% for your right knee and 20% for your left knee:

Combine the pair under § 4.25: 30 + (20% of the remaining 70) = 30 + 14 = 44.
Add 10% of that value: 44 + 4.4 = 48.4.
Round to the nearest whole number: 48. (The regulation's own example carries 20.9 forward as 21 — the decimal is never kept.)
Treat 48 as one disability and combine it with your remaining ratings, largest first.
Round the final combined value to the nearest 10 (values ending in 5 round up) per § 4.25(a).

If those two knees are your only rated conditions, the bilateral factor is the difference between a 40% combined rating (44 without it) and a 50% combined rating (48 with it) — a meaningful monthly difference.

The regulation's own example

Section 4.26 walks through a veteran rated 60%, 20%, 10%, and 10%, where the two 10s are a bilateral pair: the 10s combine to 19, the factor adds 1.9 for 21, and the ratings are then re-ranked as 60, 21, 20 — combining to 68, then 74, which converts to a 70% combined rating.

What qualifies — and what doesn't

Qualifies: compensable (10%+) ratings on both upper extremities or both lower extremities — any location, any condition type. The conditions don't have to match: a left knee and a right hip qualify (both lower extremities). The regulation's own example pairs a right thigh amputation with left-foot pes planus.
All four extremities: if both arms and both legs are affected, all four ratings are combined in order of severity and a single 10% factor is added to that one value (§ 4.26(b)) — not two separate factors.
Does not qualify: one arm plus one leg (not "paired extremities"); a pair where one side is rated 0% (each side must be compensable, § 4.26(c)); non-extremity conditions like the back, PTSD, or tinnitus; and paired organs (eyes, ears, kidneys, lungs) — those fall under a separate rule (38 U.S.C. § 1160 / 38 CFR § 3.383), not the bilateral factor.

The 2023 change most guides miss

Effective April 14, 2023, the VA added paragraph (d) to § 4.26 (88 FR 22917): if including one or more bilateral disabilities in the bilateral-factor calculation would actually produce a lower combined evaluation, the VA must exclude them from the calculation and combine them separately — whichever computation is most favorable to you controls. In plain terms: since 2023, the bilateral factor can only help your combined rating, never hurt it. Older articles that warn the factor can occasionally work against you are out of date.

See it applied to your ratings

You don't need to do any of this arithmetic by hand. Enter each rating into the 2026 VA Disability Calculator, mark the bilateral conditions, and it applies § 4.25 and the bilateral factor in the correct order and shows your monthly pay.

See how the bilateral factor changes your combined rating

Calculate Your Combined Rating

Sources & verification: 38 CFR § 4.26 (bilateral factor; amended by 88 FR 22917, effective April 14, 2023) and 38 CFR § 4.25 (combined ratings table). Verified against the current eCFR text, June 2026 — see our data & methodology. This is general information, not legal advice.