The Bilateral Factor: The Rating Bump Most Veterans Never Claim

There is a line in the rating regulations that VA is supposed to apply on its own, without you asking, and that gets missed in decisions constantly. It is 38 CFR § 4.26, the bilateral factor.

Before we go anywhere, let me correct the version of this you have probably read on a forum.

The bilateral factor is not a flat 10 percent added to your overall rating. It is 10 percent of the combined value of the bilateral disabilities only, added to that combined value, before the result gets combined with your other disabilities and before any rounding.

That distinction matters, because the two readings produce different numbers, and the wrong one sets people up for disappointment.

What qualifies as bilateral

The regulation covers paired skeletal muscles or paired extremities. In practice:

• Both arms, or disabilities of both upper extremities
• Both legs, or disabilities of both lower extremities
• Paired skeletal muscles
• Any combination of one upper and one lower extremity — for example a right shoulder and a left knee

Two things it does not cover:

• Paired organs. Both ears, both eyes, both kidneys, both lungs — no bilateral factor. Hearing loss in both ears is rated under a single table that already accounts for both sides.
• The same limb twice. A right knee and a right ankle are not bilateral with each other. Two conditions in the same extremity get combined normally.

One useful subtlety: a condition rated on the spine does not qualify, but radiculopathy of the right leg and radiculopathy of the left leg from that same spine condition are two lower extremities, and they do.

The order of operations

This is where decisions go wrong. The sequence is fixed:

1. Combine only the bilateral disabilities using the combined ratings table in § 4.25.
2. Take 10 percent of that combined value and add it. Do not round yet.
3. Treat that total as a single figure and combine it with your remaining, non-bilateral disabilities.
4. Round to the nearest 10 only at the very end.

Rounding early is the single most common way the bilateral factor gets quietly erased from a decision.

Worked example one: two knees

A veteran is rated 20 percent for the right knee and 10 percent for the left knee, with nothing else.

• Combine the two: 20 percent leaves 80 percent of the body unaffected. Ten percent of that remaining 80 is 8. So 20 + 8 = 28.
• Bilateral factor: 10 percent of 28 is 2.8. So 28 + 2.8 = 30.8.
• Nothing else to combine. Round: 30 percent.

Without the bilateral factor, 28 rounds to 30 as well. So in this specific case it changed nothing. That is honest, and it is why you should never assume the factor is automatically money.

Worked example two: where it actually pays

Now the same veteran also has a 30 percent rating for a non-bilateral condition — say migraines.

Done correctly

• Bilateral pair combines to 28, plus the 2.8 factor equals 30.8.
• Combine 30.8 with 30: the remaining unaffected portion is 69.2 percent. Thirty percent of 69.2 is 20.76. So 30.8 + 20.76 = 51.56.
• Round at the end: 50 percent.

Done wrong, with early rounding

• Bilateral pair combines to 28, rounded prematurely to 30.
• Combine 30 with 30 and you get 51, which also rounds to 50.

Still 50. Now change one number — make the migraines 50 percent instead of 30.

• Correct: 30.8 combined with 50 gives 30.8 + 34.6 = 65.4, which rounds to 70 percent.
• Bilateral factor skipped entirely: 28 combined with 50 gives 28 + 36 = 64, which rounds to 60 percent.

That is a full ten-point step, and at those levels the monthly difference is substantial and compounds over years of back pay. This is the shape of the case worth checking.

How to tell whether VA applied it

Pull your rating decision or your code sheet and look for these tells:

• An explicit line reading "bilateral factor" with a decimal value, often shown as 2.8, 5.7, and so on.
• A diagnostic code 9999 or a similar placeholder entry that exists only to carry the bilateral figure.
• A combined rating that is one step higher than your own arithmetic without the factor produces.

If you have ratings for both legs, both arms, or one arm and one leg, and none of those markers appear anywhere in the decision, that is a specific, checkable error — not a matter of opinion.

What to do about it

A missed bilateral factor is a math and law error on the face of the decision, not a disagreement about your medical evidence. That points you toward a Higher-Level Review (VA Form 20-0996), which is designed for exactly this: a more senior reviewer looks at the same evidence and corrects a mistake in how the rules were applied. You do not submit new evidence with an HLR, and doing so is a common own-goal.

If the error goes back years, ask specifically about clear and unmistakable error, which has its own much higher standard but no time limit. That is a conversation to have with someone who will read the full file.

Three things to remember

• The factor applies to paired extremities and paired skeletal muscles, not paired organs.
• It is 10 percent of the bilateral combined value, applied before combining with anything else and before rounding.
• VA is supposed to apply it without being asked — which is exactly why nobody notices when it is missing.

Run your own numbers. If they do not match the decision, you have found something worth pursuing.