50% + 30% = 65%, not 80%. The VA uses a "whole person" efficiency formula that surprises almost every veteran. Here's the actual math — and a calculator that does it for you.
Add each rated disability. Check "Bilateral" if it affects a paired extremity (both arms, both legs). Results update instantly.
The VA treats you as a whole person with 100% "efficiency." Each disability takes a percentage of whatever efficiency remains — not of the original 100%.
Think of it like stacking discounts: a 50% rating removes half your efficiency, leaving 50%. A 30% rating then removes 30% of that remaining 50% — which is only 15 points — leaving 35% efficiency. Combined rating = 100% − 35% = 65%, not 80%.
This is why combined ratings grow smaller the more conditions you add, and why reaching 100% through the schedule is essentially impossible regardless of how many conditions you have.
The legal source: This formula is codified at 38 CFR § 4.25. VA raters and BVA judges must follow it. Any combined rating that deviates from this formula is an error of law.
If you have service-connected disabilities affecting paired extremities — both arms, both legs, or a combination of one arm and one leg — you're entitled to a bilateral factor under 38 CFR § 4.26.
How it works:
Worked example: Left knee 30%, right knee 20%. Combined = 44%. Bilateral adjustment: 44% × 1.10 = 48.4% (rounds to 48%). That 48% now enters the rest of your combined-ratings calculation. Without the bilateral factor you'd use 44% — a 4-point swing that can flip your final rating by 10%.
The calculator above handles bilateral factor automatically. Check the "Bilateral" box on any extremity disability to include it.
Source: 38 CFR § 4.26 — Bilateral factor
These three examples show cases where adding ratings would give a completely wrong answer. The VA math consistently produces a lower combined figure than simple addition.
| Ratings | Wrong (simple addition) | Correct VA math | Rounded final |
|---|---|---|---|
| 50% + 30% | 80% | 65% | 70% |
| 60% + 40% + 20% | 120% (capped at 100%) | 80.8% → rounds to | 80% |
| 70% + 50% + 30% + 20% | 170% (impossible) | 87.3% → rounds to | 90% |
Notice that 60% + 40% + 20% doesn't reach 100% even though their sum exceeds it. This is deliberate VA policy: the whole-person model means no veteran can reach 100% through ratings accumulation alone regardless of how many conditions they add.
Your combined rating determines your compensation tier — but it also opens or closes other options.
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