VA Math Guide · High impact
Bilateral factor 2026: the most-missed money in VA Math
The bilateral factor — 38 CFR §4.26 — is the single biggest source of "VA Math errors" we see in the wild. Most veterans don't know it exists. Many calculators apply it in the wrong order. Done correctly, it can bump you up a full tier and add $400+/month before dependents.
When it applies
§4.26 applies to service-connected disabilities affecting both arms, both legs, or paired skeletal muscles. It does NOT apply to cross-pairings (left knee + right wrist), or to single-side conditions even when severe.
The correct sequence (this matters)
- Identify the paired-group conditions.
- Combine the paired group among itself using the regular §4.25 formula. Call the result G.
- Add 10% of G to G itself. The new value is G × 1.10.
- Treat the bilateral group as a single disability rated at G × 1.10.
- Combine that single value with all your non-bilateral ratings using §4.25.
- Round the FINAL number to the nearest 10%.
Worked example — 20% left knee + 20% right knee + 10% tinnitus:
- Combine the two knees: combine(20, 20) = 36%.
- Bilateral bonus: 36 × 0.10 = 3.6 → bilateral group = 39.6%.
- Fold tinnitus: combine(39.6, 10) = 45.64%.
- Round → 50% combined.
Without the bilateral bonus, the same conditions combine to 42.4% → rounded to 40%. The bilateral factor in this example is the difference between a 40% rating and a 50% rating — worth roughly $337/month before dependents.
§4.26(d) — the "higher path" rule
If applying the bilateral bonus would actually produce a lower final combined rating (it happens in rare edge cases around bracket boundaries), VA uses the path WITHOUT the bonus. Our calculator computes both paths and picks the higher.
FAQ
Does bilateral factor apply to left knee + right wrist?
No. The bilateral factor applies to paired upper extremities (both arms) OR paired lower extremities (both legs) OR paired skeletal muscles — not cross-pairings like one arm + one leg.
Is the 10% added to my total or to the sub-total?
To the sub-total of the paired group. Combine left and right within the pair first, take 10% of that, add it to the same sub-total, then fold the result into the rest of your ratings as a single number.
Can the bilateral factor lower my rating?
No — per §4.26(d), if using bilateral produces a LOWER final rating than not using it, VA uses the higher path. Our calculator computes both and picks the higher automatically.