The Bilateral Factor, How VA Adds 10 Percent for Paired Body Parts

The bilateral factor is small, misunderstood, and worth real money in both directions. It is not a separate rating: it is 10 percent of the bilateral group's value, added before the rest of the combined math. And since April 2023, VA must also check whether leaving the factor out produces the higher combined rating, because near the top of the table the factor can actually work against you.

Purpose of this article

VA's combined rating math under 38 CFR 4.25 is already non-intuitive. Add the bilateral factor from 38 CFR 4.26, and the math gets one more layer. The bilateral factor is a 10 percent bonus added BEFORE the VA math combination kicks in, but only when two paired body parts are both rated. This article walks through when the factor applies, the worked math, and why most veterans either over-estimate or miss the factor entirely.

This is educational, not legal advice.

Rule overview

Under 38 CFR 4.26, when both arms, both legs, OR the muscles or paired body parts on opposite sides of the body are affected by disabilities that are rated under the rating schedule, an additional 10 percent is added to the value of the affected body parts BEFORE the combined rating math.

The factor only adds to the value of the bilateral group. It does not add to any non-bilateral rating.

Worked example

A veteran has the following ratings:

• Right knee, 30 percent.
• Left knee, 30 percent.
• Tinnitus, 10 percent.

Step 1, group the bilateral ratings. The right and left knees are paired. Tinnitus is not paired.

Step 2, combine the bilateral group under 38 CFR 4.25.

• 30 percent combined with 30 percent = 30 + (100 - 30) * 0.30 = 30 + 21 = 51 percent.

Step 3, apply the 10 percent bilateral factor to the bilateral group total.

• 51 + (51 * 0.10) = 51 + 5.1 = 56.1, which rounds down to 56.

Step 4, combine the bilateral-group total with the non-bilateral ratings under 38 CFR 4.25.

• 56 combined with 10 (tinnitus) = 56 + (100 - 56) * 0.10 = 56 + 4.4 = 60.4

Step 5, round to the nearest 10 for the schedular award.

• 60.4 rounds to 60.

Final rating: 60 percent.

Without the bilateral factor, the veteran's rating would have been:

• 30 combined with 30 = 51, then combined with 10 = 56.

A difference of 4 percentage points, which can push the veteran above or below a 10-percent threshold and meaningfully change the monthly payment.

Which body parts are "paired" for the bilateral factor

The regulation specifies the bilateral factor applies when EITHER:

• The arms (both upper extremities) are rated, OR
• The legs (both lower extremities) are rated, OR
• The skeletal muscles, joints, or other body parts on opposite sides of the body are rated.

In practice:

• Both knees (one of each side): YES.
• Both shoulders (one of each side): YES.
• Both feet (one of each side): YES.
• Both ears (one of each side, for hearing loss): YES, in some readings, but VA generally does NOT apply the bilateral factor to hearing loss because hearing loss is rated as a single bilateral rating under DC 6100 already.
• Both kidneys (one of each side): NO, because the kidneys are rated together (as renal function), not separately.
• One arm and one leg on opposite sides: NO, because these are not paired body parts.
• Both eyes: NO, because vision is rated under separate bilateral rules.

When the bilateral factor does NOT apply

Three situations where veterans sometimes expect the bilateral factor but it does not apply:

• One paired rating is for a NON-skeletal/muscular condition. Example: a veteran has a service connected right elbow at 20 percent and a service connected left elbow neuropathy at 10 percent (rated under the peripheral nerves section, not the muscle or joint section). The bilateral factor may still apply because both elbows are paired, but the question is whether the conditions are rated under sections that the regulation includes. Most VA decisions interpret this broadly: anything affecting both sides of the same body part gets the factor.
• Bilateral hearing loss. Already rated as a single bilateral rating under DC 6100. The factor does NOT add.
• The same body part rated twice for different conditions. Example: a veteran has the right knee rated 20 percent for instability AND 10 percent for limitation of motion. The bilateral factor does NOT apply to the same knee combined with itself. The two right-knee ratings combine under 38 CFR 4.25 without the bilateral factor.

Why the bilateral factor is often overlooked

Most veterans (and many representatives) do the combined rating math without remembering the bilateral factor. The VA decision will usually apply the factor correctly when the ratings are obvious, but in complex multi-condition cases, the factor sometimes gets overlooked.

If a veteran's rating decision letter combines bilateral conditions and produces a final percentage that seems low, it is worth recalculating with the bilateral factor explicitly.

How to ask VA to correct a missed bilateral factor

If a final VA rating decision combined bilateral ratings without applying the 10 percent factor, the veteran can:

1. File a Higher Level Review (HLR) under the AMA, asking for a senior reviewer to look at the combined rating math. Time-sensitive: the AMA HLR window is one year from the decision date.
2. If the HLR is denied or upholds the same math, file a Supplemental Claim with the corrected calculation as evidence.
3. If the AMA review lanes do not produce a correction, file a CUE motion under 38 CFR 3.105(a) asserting that the prior decision misapplied 38 CFR 4.26. CUE motions on math errors are among the more successful CUE types.

Common misunderstandings

• The bilateral factor is not a separate rating. It is a 10 percent multiplier applied to the bilateral group total BEFORE combining with non-bilateral ratings.
• The 10 percent factor does NOT apply to the non-bilateral ratings. It only applies to the bilateral group.
• Three or more paired ratings on the same body still only get one 10 percent factor (the factor is on the bilateral group as a whole, not per pair).
• Rounding happens at the end. The intermediate bilateral-group total is not rounded before combining with non-bilateral ratings.

Sources

• 38 CFR 4.25 (combined ratings table)
• 38 CFR 4.26 (bilateral factor)
• VA M21-1, Part III, Subpart iv, Chapter 6, Section A (combined rating procedures)
• 38 CFR 3.105(a) (CUE on math errors)

The April 2023 exception under 38 CFR 4.26(d)

Effective April 16, 2023, VA added an exception to the bilateral factor rule through an interim final rule (88 FR 22914). Near the top of the rating scale, the factor can actually work against a veteran. The factor turns several paired ratings into one larger unit, and one larger unit sometimes climbs the combined ratings table more slowly than the separate ratings would on their own.

Under 38 CFR 4.26(d), when leaving one or more bilateral disabilities out of the factor calculation and combining them separately produces a higher combined evaluation, VA must use the higher result.

A worked example. A veteran is rated 70, 50, 40, and 20 percent, plus 10 percent in each knee.

• With the factor: the two 10s combine to 19, plus 1.9 for the factor, which rounds to 21. The list 70, 50, 40, 21, 20 climbs the table to 94, which converts to a 90 percent combined rating.
• Without the factor: the list 70, 50, 40, 20, 10, 10 climbs step by step to 95, which converts to 100 percent.

Under the exception, VA must use the 100 percent result. VA stated it would adjust affected ratings on its own initiative. If you believe a decision issued before the rule still reflects the lower number, a VA accredited representative can review the math with you, and you can ask VA to audit the calculation.

Our bilateral factor calculator and combined rating calculator check both methods automatically and always report the higher result.

When you check your combined rating math, ask

• Are the grouped ratings actually paired body parts (both arms, both legs, or opposite-side parts), not the same joint rated twice for different problems?
• Was the 10 percent factor applied to the bilateral group total before combining with the non-bilateral ratings (38 CFR 4.26)?
• Was hearing loss left out of the factor, since DC 6100 already rates both ears as a single evaluation?
• Was the math run both ways under 38 CFR 4.26(d), since skipping the factor sometimes produces the higher combined rating?
• If a final decision missed the factor, is a Higher Level Review or a CUE motion under 38 CFR 3.105(a) the right correction lane?

Related on this site

• VA Math: How Combined Ratings Really Work