The combined rating table in 38 CFR 4.25 is used to calculate a veteran's combined disability percentage when multiple service-connected conditions are rated. The VA does not add ratings — it combines them using a formula that reflects diminishing impact on overall health.
The process works as follows: start with the highest-rated disability and apply each additional disability to the remaining "healthy" percentage. For a practical example, consider a veteran with three rated conditions at 40%, 20%, and 10%.
Start with 40%. The remaining healthy percentage is 60%. Apply 20% to that remaining 60%: 20% of 60% = 12%. Combined value so far: 40% + 12% = 52%. Remaining healthy percentage: 48%. Apply 10% to that remaining 48%: 10% of 48% = 4.8%. Combined value: 52% + 4.8% = 56.8%. Round to the nearest 10%: 56.8% rounds up to 60%.
The order in which you combine the ratings does not affect the final result — the math produces the same combined value regardless of sequence.
Rounding rules: the final combined value is rounded to the nearest 10%. Values ending in 5 through 9 round up; values ending in 1 through 4 round down. This rounding can mean the difference between significant compensation tiers.
The bilateral factor (38 CFR 4. The VA is required to calculate your combined rating both with and without the bilateral factor and use whichever method produces the higher result for the veteran.26) modifies the calculation for paired limb disabilities by adding 10% to the combined value of the bilateral conditions before combining with other ratings.
Strategic implications: because of VA math, each additional disability has diminishing returns on the combined percentage. Getting from 0% to 50% is easier than getting from 80% to 90%. However, even small additional ratings can push a combined value past a rounding threshold. A veteran at 64% combined (which rounds to 60%) who adds a 10% rating may reach 68% (which rounds to 70%), gaining a full tier of compensation from a single additional small rating.
Note: This article references sections of the VA's M21-1 Adjudication Procedures Manual. The VA periodically reorganizes the M21-1 and section numbers may have changed since this article was written. For the most current section references, visit the VA's public M21-1 Web Automated Reference Material System (WARMS).