The VA Bilateral Factor: How Paired Conditions Add 10% to Your Rating
If you have service-connected conditions affecting both arms, both legs, or paired skeletal muscles, the VA is required to apply a 10% increase to the combined value of those conditions before factoring them into your overall rating. Most veterans have never heard of this. Some raters forget to apply it. Here is how it works and how to verify it was applied to your rating.
What Is the Bilateral Factor?
Under 38 C.F.R. § 4.26, when a veteran has service-connected disabilities affecting both upper extremities, both lower extremities, or paired skeletal muscles, the VA adds 10% to the combined degree of those bilateral disabilities before merging them into the overall combined rating under 38 C.F.R. § 4.25.
The rationale is straightforward: having both knees injured is more debilitating than having one knee and one unrelated condition at the same percentages. When both sides are affected, the compensating mechanism is gone. You cannot favor the other leg if both legs are damaged.
Which Conditions Qualify?
Both lower extremities: Bilateral knee conditions (flexion, extension, instability), bilateral ankle conditions, bilateral hip conditions, bilateral plantar fasciitis, bilateral lower extremity radiculopathy, bilateral pes planus (flat feet)
Paired skeletal muscles: Bilateral muscle injuries affecting the same muscle group on both sides
Bilateral hearing loss: Rated under 38 C.F.R. § 4.85 (the bilateral factor is built into the hearing loss rating tables, so it is already reflected in the single combined rating for hearing loss)
Internal organs: GERD, IBS, heart conditions, respiratory conditions, and other organ-based disabilities
Mental health: PTSD, depression, anxiety, and all mental health conditions rated under 38 C.F.R. § 4.130
Unpaired conditions: A right knee and a left shoulder are not bilateral for purposes of 4.26 because they affect different extremity groups
The Math: How the Bilateral Factor Works
The bilateral factor calculation follows a specific sequence defined in 38 C.F.R. § 4.26. Here is a concrete example:
Right knee limited flexion: 10%
Right knee instability: 10%
Left knee limited flexion: 10%
Left knee instability: 10%
PTSD: 50%
10% + 10% + 10% + 10% = 34.39% combined
(10 + 9 + 8.1 + 7.29 = 34.39)
34.39 x 0.10 = 3.439
34.39 + 3.439 = 37.83 (round to 38%)
50% + 38% of remaining 50% = 50 + 19 = 69%
Rounded to: 70%
Combining all five conditions straight: 50 + 10 + 9 + 8.1 + 7.29 = 64.39 → rounds to 60%
With bilateral factor: 70%
Difference: $375.74/mo ($4,508.88/yr)
How to Verify the Bilateral Factor Was Applied
Your rating decision letter (also called a rating codesheet) should explicitly state whether the bilateral factor was applied. Look for language such as "bilateral factor of X.X% added" or a line item showing the bilateral factor calculation. If you have bilateral conditions and your codesheet does not mention the bilateral factor, it may not have been applied. This is a common error and grounds for a Higher-Level Review under VA Form 20-0996 citing failure to apply 38 C.F.R. § 4.26.
The Claim Recon calculator applies the bilateral factor automatically when you designate conditions as bilateral. Use it to verify whether your current combined rating matches what it should be with the bilateral factor correctly applied.
Common Bilateral Combinations in VA Claims
Bilateral plantar fasciitis / pes planus: Extremely common in combat arms MOSs. Rated under DC 5276 (pes planus) or DC 5284 (foot injuries). Both feet affected means bilateral factor applies.
Bilateral lower extremity radiculopathy: Secondary to lumbar spine conditions. Rated under DC 8520 (sciatic nerve). When the back condition causes radiculopathy in both legs, each leg is rated separately and the bilateral factor applies to the pair.
Bilateral upper extremity radiculopathy: Secondary to cervical spine conditions. Rated under DC 8510-8519 depending on the nerve involved. Both arms affected = bilateral factor.
Bilateral carpal tunnel: Common in MOSs involving repetitive hand use (mechanics, communications, signal). Rated under DC 8515 (median nerve). Both wrists = bilateral factor.
Bilateral shoulder conditions: Common in aviation (helmet/NVG weight), airborne (PLF impacts), and any MOS with overhead lifting. Both shoulders = bilateral factor.
Regulatory Citations
38 C.F.R. § 4.25 — Combined ratings table (standard VA math)
38 C.F.R. § 4.26a — Paired organs and extremities defined
38 C.F.R. § 4.71a — Schedule of ratings for musculoskeletal system
38 C.F.R. § 4.85 — Hearing loss evaluation (bilateral factor built into tables)
VAOPGCPREC 23-97 — Separate ratings for arthritis and instability in same knee
VAOPGCPREC 9-04 — Separate ratings for flexion and extension in same knee
M21-1, Part IV.ii.2 — Rating musculoskeletal conditions