The bilateral factor is one of the most overlooked rules in VA disability — an automatic 10% boost when disabilities affect paired parts of your body. It can be the difference between two rating levels, and many veterans never realize they qualify.
What the bilateral factor is
Under 38 CFR §4.26, when you have compensable disabilities affecting both arms, both legs, or paired skeletal muscles, the VA combines those paired disabilities first and then adds 10% of the combined value before working them into the rest of your rating.
The idea: losing function on both sides of the body is more disabling than the same losses on one side. Two bad knees limit you more than one bad knee and one bad shoulder — when both legs are compromised, there's no good side to shift your weight to. So the regulation rewards the bilateral pattern with a measured bump before the ordinary VA math takes over.
How it's calculated
The bilateral factor is applied in a specific order:
- Combine the bilateral disabilities together using normal VA math (§4.25).
- Add 10% of that combined value (this is the bilateral factor).
- Round to the nearest whole number — the result is treated as one single rating, the "bilateral value."
- Combine that value with your remaining, non-bilateral ratings, ordered by size like any other rating.
- Round the final total to the nearest 10%.
Note the two different roundings: the bilateral value rounds to the nearest whole number (39.6 becomes 40), while the final combined value rounds to the nearest 10 at the very end. The first rounding happens before the second, and both can work in your favor.
Worked example
Say you have a 40% right knee and a 20% left knee — a classic bilateral pair — plus a 30% back condition.
- Combine the two knees: 40 + (20% × the remaining 60) = 40 + 12 = 52.
- Add the 10% bilateral factor: 52 + 5.2 = 57.2, rounded to 57.
- Now combine 57 with the 30% back: 57 + (30% of the remaining 43) = 57 + 12.9 = 69.9 → 70.
- Final rating: 70%.
Without the bilateral factor, those same three ratings (40, 30, 20) combine to a value of 66.4 — which still rounds to 70%, but with much less cushion. In many real cases the extra points are exactly what push a veteran from one level to the next, as the example below shows.
Small ratings work the same way. Two 10% feet: 10 + (10% × 90) = 19; add 1.9 for the factor to get 20.9; round to 21. That 21 — not 19 — is what enters the rest of your combination, two extra points for the same two conditions.
When the factor changes your whole rating level
Most of the time the bilateral factor adds a few points of cushion. Sometimes it moves you across a rounding line — and that's worth real money. Take a veteran with a 60% condition plus two 20% knees:
- Without the factor: 60 + (20% × 40) = 68; then 68 + (20% × 32) = 74.4 → rounds to 70%.
- With the factor: knees first: 20 + 20 combine to 36; add 3.6 → 39.6 → bilateral value 40. Then 60 + (40% × 40) = 60 + 16 = 76 → rounds to 80%.
Same three conditions, one level apart. In 2026 that's $2,102.15 a month at 80% instead of $1,808.45 at 70% for a veteran alone — $293.70 more every month, or $3,524.40 a year, from a rule many veterans have never heard of. The gain comes from both pieces: the added 10%, and the bilateral value rounding up to 40 before it's combined. Check what each level pays on the 2026 pay chart.
Why it's so easy to miss
The bilateral factor is applied automatically by the VA when the conditions qualify — there's no box to check on a claim form. But it only happens if the disabilities are correctly identified as bilateral in your rating decision. If a knee was rated without noting the other knee, or a left-foot condition was never paired with the right, the factor can be left out of the combined-rating worksheet. Reviewing your rating decision for paired conditions is one of the simplest ways to find money you may be owed — and if you're close to a threshold like 95 for a schedular 100%, it can matter even more (see going from 90% to 100%).
What counts as "paired"
- Yes: right knee + left knee; right wrist + left wrist; right foot + left foot; left knee + right ankle (both lower extremities — the joints don't have to match); paired skeletal muscle groups.
- No: one knee + lower back (the back isn't a paired extremity); right knee + right ankle (same side); one arm + one leg (an upper and a lower extremity don't pair); tinnitus + a single shoulder.
The ratings also have to be compensable — a 0% rating on one side doesn't create a bilateral pair. When in doubt, leave the box unchecked in the calculator; that gives you the conservative (lower) estimate. If you think you qualify, an accredited VSO or claims representative can confirm whether your conditions meet §4.26.
Frequently asked questions
Do the disabilities have to be the same joint on each side?
No. The factor applies to compensable disabilities of both upper or both lower extremities — they don't have to be the same joint. A left knee paired with a right ankle qualifies, because both are lower-extremity disabilities.
Does one arm and one leg qualify?
No. The pairing is both arms or both legs (or paired skeletal muscles). An arm disability plus a leg disability isn't a bilateral pair under §4.26, no matter which sides they're on.
How much does the bilateral factor actually add?
10% of the combined value of the paired ratings — usually a few points. Two 20% knees combine to 36; the factor adds 3.6, and the 39.6 rounds to a bilateral value of 40. Small on its own, but near a rounding threshold those points can lift your whole rating a level.
Do I need to apply for it?
No — the VA applies it automatically when qualifying paired disabilities exist. But automatic only works when the pairing is recognized, so check your rating decision to confirm the bilateral factor appears in the combined-rating calculation.
Can it really change my overall rating level?
Yes. A 60% condition plus two 20% knees is 74.4 without the factor — paid as 70% — but 76 with it, paid as 80%. In 2026 that's $293.70 a month more for a veteran alone.