The bilateral factor is one of the few rules in the VA rating system that works entirely in your favor. When you have service-connected disabilities affecting both sides of a paired body part, the VA adds a bonus before combining those ratings with the rest of your conditions.
Most veterans either do not know it exists or assume the VA applied it correctly. Neither assumption is safe.
This calculator applies the bilateral factor automatically. Enter your paired conditions, add any non-bilateral ratings, and see how your combined rating changes with and without the factor applied.
What Is the Bilateral Factor?
The bilateral factor is defined in 38 CFR 4.26. It recognizes that losing function on both sides of your body is more disabling than losing the same total function on one side. Walking with one bad knee is hard. Walking with two bad knees affects your balance, your gait, and your entire daily function in a way that compounds the individual impairments.
The VA accounts for this by adding 10% of the combined bilateral rating to those paired conditions before incorporating them into your overall combined rating.
The bilateral factor does not create a separate payment line on your award letter. It changes the number that goes into the final combined rating calculation. In a system where a single percentage point determines whether your combined rating rounds up or rounds down, even small additions matter.
Which Conditions Qualify
The bilateral factor applies to disabilities affecting the upper extremities or the lower extremities. Both conditions must fall in the same group.
Upper extremities include any service-connected condition from the shoulders down to the hands. Both shoulders, both arms, both elbows, both wrists, both hands.
Lower extremities include any service-connected condition from the hips down to the feet. Both hips, both legs, both knees, both ankles, both feet.
The conditions do not have to be the same diagnosis. A right knee rated under DC 5260 and a left ankle rated under DC 5271 both involve lower extremities. The bilateral factor applies. A right shoulder injury and a left shoulder injury both involve upper extremities. The bilateral factor applies.
What does not qualify:
A right shoulder condition and a left knee condition do not trigger the bilateral factor. They are not the same paired group. Upper and lower extremities do not mix for bilateral factor purposes.
Tinnitus does not qualify. The VA explicitly states in the notes to Diagnostic Code 6260 that only one evaluation is assigned for tinnitus regardless of how many ears are affected. There is no bilateral factor for auditory conditions rated as a single evaluation.
Back conditions, PTSD, sleep apnea, and most internal conditions do not qualify because they are not extremity conditions.
How the Math Works
The bilateral factor calculation follows a specific four-step sequence under 38 CFR 4.25 and 38 CFR 4.26.
Step 1. Combine the paired bilateral ratings using standard VA math. This means applying each rating to the remaining healthy percentage, not adding them together.
Step 2. Multiply the combined bilateral value by 10%. This is the bilateral factor addition.
Step 3. Add that 10% amount back to the combined bilateral value. The result is your bilateral subtotal.
Step 4. Combine the bilateral subtotal with all remaining non-bilateral service-connected conditions using standard VA math. Apply ratings highest to lowest.
The bilateral subtotal is treated as a single rating in the final combination. It enters the calculation before the other conditions only in the sense that it has already been processed as one unit.
Three Real Examples
Example 1: Both Knees
Right knee rated at 20%. Left knee rated at 10%.
Step 1: Combine the two knee ratings. Start with 20% applied to 100% efficiency. 80% remains. Apply 10% to the remaining 80%. That adds 8%. Combined bilateral value: 28%.
Step 2: Bilateral factor. 10% of 28 = 2.8%.
Step 3: Bilateral subtotal. 28 + 2.8 = 30.8%.
Step 4: If the veteran's only other condition is PTSD at 70%, combine 70% and 30.8%. Start with 70% applied to 100% efficiency. 30% remains. Apply 30.8% to the remaining 30%. That adds 9.24%. Combined: 79.24%. Rounds to 80%.
Without the bilateral factor the same veteran has 70% PTSD plus 28% bilateral knees. Combined: 78.4%. Rounds to 80%.
In this case the rounding works out the same. But move the numbers slightly and the bilateral factor is the difference between rounding up and rounding down. That threshold is where the factor earns its value.
Example 2: Both Shoulders
Right shoulder rated at 30%. Left shoulder rated at 20%.
Step 1: Combine. Start with 30%. 70% remains. Apply 20% to 70%. That adds 14%. Combined bilateral value: 44%.
Step 2: Bilateral factor. 10% of 44 = 4.4%.
Step 3: Bilateral subtotal: 44 + 4.4 = 48.4%.
Step 4: Combine with tinnitus at 10% and sleep apnea at 50%. Start with sleep apnea at 50%. 50% remains. Apply bilateral subtotal of 48.4% to 50%. That adds 24.2%. Running total: 74.2%. Apply tinnitus 10% to remaining 25.8%. Adds 2.58%. Final combined: 76.78%. Rounds to 80%.
Example 3: Mixed Lower Extremities
Right knee at 10%. Left ankle at 10%. These are different joints but both lower extremity conditions. The bilateral factor applies.
Step 1: Combine. Start with 10%. 90% remains. Apply 10% to 90%. Adds 9%. Combined bilateral value: 19%.
Step 2: Bilateral factor. 10% of 19 = 1.9%.
Step 3: Bilateral subtotal: 19 + 1.9 = 20.9%.
This is a modest gain but it enters the final combined rating at 20.9% rather than 19%. In combination with several other conditions, that 1.9% can be the difference between a combined rating that rounds to 60% versus 70%.
Common Mistakes Veterans Make
Assuming the VA applied it automatically and correctly. The VA should apply the bilateral factor in every eligible case. But mistakes happen. Rating decisions do not always show the step-by-step math. Look in the reasons and bases section of your decision letter for language referencing the bilateral factor or 38 CFR 4.26. If it is not mentioned and you have bilateral conditions, it may not have been applied.
Thinking the conditions have to be the same diagnosis. They do not. Right knee flexion limitation and left hip instability are different diagnoses. Both are lower extremity conditions. The bilateral factor applies.
Not filing the second side. Many veterans file for the dominant-side injury and never document the other side. If your non-dominant knee, shoulder, or ankle has become symptomatic, file for it. Even a 0% rating on the second side may trigger the bilateral factor in combination with a compensable rating on the first side depending on your specific circumstances.
Applying it to the final combined rating. The bilateral factor applies to the paired conditions first. The adjusted bilateral subtotal is then combined with the remaining conditions. It is not added to the final combined rating as a separate step at the end. If you are calculating by hand and apply it in the wrong sequence, the result will be wrong.
Check Your Bilateral Factor Was Applied
If you have service-connected conditions affecting both upper extremities or both lower extremities, take five minutes to verify your rating decision.
Look for the phrase bilateral factor in your decision letter. Look for a reference to 38 CFR 4.26. Run the numbers manually using the steps above or use this calculator to see what your combined rating should be.
If the bilateral factor was omitted, a supplemental claim is one path to correction. A VA-accredited attorney can review your decision at no cost to determine whether an appeal or supplemental claim is appropriate.
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