VA disability · guide
The VA bilateral factor, explained with numbers
When both arms or both legs are rated, VA adds 10% before combining anything else. Here is what that changes, and when it changes your rating step.
Bilateral factor: both knees, both arms
Combined rating with the bilateral factor
60%
| Bilateral value (legs + 10%) | 21 |
| Combined value | 61 |
| Without the factor | 60 → 60% |
The bilateral factor is a rule of 38 CFR 4.26: when a veteran has compensable ratings on both arms, or both legs, or paired skeletal muscles, VA first combines those ratings, then adds 10% of the result, and treats the total as one disability before combining the others. Two knees at 10% combine to 19; the factor adds 1.9, so the bilateral disability counts as 21. The amount is small on its own, but it lands at the top of the combination, where it can push the combined value over a rounding line: knees at 20% and 20% with a back rated 40% give a combined value of 64 with the factor and 62 without it, which is the difference between 60% and 60%, or $0 a month for a veteran alone in 2026. The calculator below applies it to your own ratings.
Checked by Radif Partners · Editorial policy · How we calculate
The rule in four steps
- Take every compensable disability of the paired extremities: both arms (shoulder to hand) or both legs (hip to foot). If all four limbs are affected, all of them go in the same group.
- Combine them with the combined ratings table as if they were alone.
- Add 10% of that combined value, without combining it, and round to a whole number.
- Put the result in the list of your other ratings as one disability, in order of severity, and combine everything as usual. Round to the nearest 10 only at the very end.
The regulation gives its own example: ratings of 60%, 20%, 10% and 10%, the two 10% being bilateral. The two 10% combine to 19, plus 1.9, so 21. The order of severity becomes 60, 21 and 20; 60 and 21 combine to 68, and 68 and 20 to 74, which becomes 70%. The calculator reproduces that example exactly; it is one of the tests the site runs before each update.
Worked examples
| Ratings | Bilateral value | Combined value | Rating | Without the factor |
|---|---|---|---|---|
| Both knees 10% | 21 | 21 | 20% | 19 → 20% |
| Knees 10% and 20% | 31 | 31 | 30% | 28 → 30% |
| Knees 20% and 20%, back 40% | 40 | 64 | 60% | 62 → 60% |
| Knees 30% and 10%, PTSD 50% | 41 | 71 | 70% | 69 → 70% |
| Feet 10% and 10%, PTSD 70%, back 20% | 21 | 81 | 80% | 80 → 80% |
In most of these cases the final step does not move: the factor adds one or two points of combined value, and a rating changes only when those points cross a line that ends in 5. That is why veterans often hear that the bilateral factor "does nothing". It does something every time; whether you see it in dollars depends on where your combined value sits. A veteran at a combined 64 has everything to gain from one more point, a veteran at 66 has nothing.
Which conditions count
The paired extremities are the arms and the legs taken as wholes. A shoulder and the opposite wrist count together, a hip and the opposite ankle too. Paired skeletal muscles are the muscle groups VA rates on both sides of the body. Knees are the most common case: veterans who served long years carrying loads often have a rating on each knee, and both are compensable at 10% for painful motion. Radiculopathy of both legs, rated as nerve damage, also falls under the factor, which matters for back injuries that send pain down both sides.
What does not count: the spine itself, which is one body part; hearing loss and tinnitus; eyes; and any side rated 0%, since the regulation requires compensable disability on each side. When one knee is at 10% and the other at 0%, there is no bilateral factor at all. If the second knee is later raised to 10%, the factor starts with that new rating, so the gain is larger than the 10% alone suggests.
Why the factor exists
The combined ratings table measures how much efficiency a person keeps. Losing the use of one knee leaves the other to carry the load; losing part of the use of both leaves no healthy side to compensate. A plain combination would treat the two knees like two unrelated conditions, a knee and an ear, and understate the effect on walking, standing and climbing. The 10% added by the factor is the rough correction the rating schedule chose for that loss of a compensating limb, and it has been in the schedule since 1964 in almost the same words.
The factor also explains a pattern many veterans notice on their decision: a group of small limb ratings weighs a little more than the same ratings scattered across the body. Two ankles at 10% count as 21, while an ankle at 10% and a wrist at 10% on the same side combine to only 19, because the wrist is an arm and the ankle a leg, and neither has a rated partner on the other side.
A step-by-step case
Take a veteran with PTSD at 50%, a lower back at 20%, the right knee at 10% and the left knee at 20%. The knees combine first: 20 and 10 give 28, and 10% of that is 2.8, so the bilateral value is 31. The order of severity is now 50, 31 and 20. Fifty and 31 combine to 66; that value and 20 combine to 73. The final rating is 70%, worth $1,808.45 a month for a veteran alone in 2026. Without the factor the four ratings would combine to 71.
The exception of paragraph (d)
Since a 2023 amendment, paragraph (d) of 38 CFR 4.26 says that if the combined evaluation is lower with a bilateral disability inside the factor than outside it, VA must leave it out and combine it separately. This happens in unusual mixes of high and low ratings, where grouping a small limb rating with a large one changes the order of severity. You do not have to work it out: our engine tries each grouping of your limb ratings and keeps the best. VA raters are supposed to do the same, and a decision that applies the factor against the veteran can be challenged.
How to check your own decision
Write down each rating from the code sheet of your decision, mark the ones on the left and right arms and legs, and enter them in the VA disability calculator with the body part. The result shows the bilateral value, the combined value and the final rating. If VA's combined rating is lower, look first at whether every limb rating was included in the group; then at whether a 0% side was counted by mistake. The combined ratings table lets you redo the steps one at a time, and the 2026 rate chart gives the monthly amount at each step.