What the bilateral factor is
When the VA rates disabilities on both sides of the body that involve paired extremities or certain paired skeletal muscles, it may add a bilateral factor before finishing your combined rating. The idea is simple: losing efficiency on both sides is often harder than the same ratings on one side alone.
Under 38 CFR §4.26, the VA first combines the bilateral disabilities using the normal combined ratings table, then adds 10% of that combined bilateral value (not another combine step). That new figure is then combined with your other disabilities.
What usually counts as “bilateral”
Common examples include both knees, both hips, both ankles, or both arms/hands when the disabilities are of paired extremities. Exact pairing depends on how the VA classified the conditions on your rating decision — not every left/right pair automatically gets the factor.
- Paired extremities (arms/legs) are the classic case.
- Some paired skeletal muscle groups can qualify under the regulation.
- Hearing loss in both ears is handled under separate rules — don’t assume bilateral factor math applies the same way.
- Always check your decision letter or codesheet for how the VA listed the disabilities.
How the math works (step by step)
1) Identify which ratings the VA treated as bilateral.
2) Combine those bilateral ratings with the §4.25 table (highest first, whole-number steps).
3) Take 10% of that bilateral combined value and add it (do not combine the 10%).
4) Combine that bilateral-with-factor result with your remaining disabilities using the table again.
5) Round the final combined value to the nearest 10% (values ending in 5 round up).
Worked example
Suppose both knees are rated 10% and 10%, and you also have a separate 50% rating. Bilateral knees combine to 19. Ten percent of 19 is 1.9, which rounds into the bilateral-with-factor figure (commonly treated as about 21 before further combining). That result is then combined with the 50% using the combined ratings table, and the final number is rounded to the nearest 10% for pay. Use the calculator’s bilateral mode to walk the steps with your numbers.
Common mistakes
- Turning bilateral mode on for conditions the VA did not treat as bilateral.
- Adding 10% to each side separately instead of 10% of the combined bilateral value.
- Combining the 10% factor like another disability instead of adding it.
- Comparing your deposit to a bilateral estimate when your letter never applied the factor.
What to do next
Run your ratings in the combined rating calculator with bilateral mode on only for the pairs you believe the VA treated that way. Then compare the rounded result to your decision letter. If the letter’s combined rating matches ordinary combining but not bilateral combining, the VA may not have applied §4.26 — that is a conversation for a VSO, not a guarantee of error.