Bilateral factor

The bilateral factor is an extra step in the VA's combining math, and it applies when a partial disability affects both arms, both legs, or paired skeletal muscles. Under 38 CFR 4.26 the evaluations for the two sides are combined as usual, then 10 percent of that combined value is added rather than combined, before any further combination and before any conversion to a final degree of disability.

Two conditions decide whether it applies at all. Each side of the pair must carry an evaluation above 0 percent, since 38 CFR 4.26(c) requires partial disability of compensable degree in each of two paired extremities. And the pair has to be a real one: paragraph (a) treats each upper extremity and each lower extremity as a whole, so a right thigh and a left foot qualify while an arm and a leg do not.

Order matters here. The bilateral group is worked first, comes out as a single number, and is then treated as one disability for every combination after it. Where all four extremities are affected, paragraph (b) directs a single group carrying one 10 percent addition rather than a separate addition for the arms and another for the legs. Whether the factor was applied correctly on a particular decision is claims work, and a VA-accredited VSO representative will read the letter with a veteran at no charge.