Why VA Math Is Not Simple Addition
VA disability ratings are combined, not simply added together. That means a 50% rating and a 30% rating do not equal 80%.
Think of a veteran as starting with 100 points of overall ability. A 50% disability rating accounts for 50 of those points, leaving 50 points unaffected. The next 30% rating is then applied only to the 50 points that remain—not to the original 100.
Here is how that example works:
The first disability is 50%.
That leaves 50% remaining.
The second disability is 30% of the remaining 50%.
Thirty percent of 50 is 15.
Add that 15 to the original 50, and the combined value is 65%.
VA then rounds the final combined value to the nearest 10%. In this example, 65% rounds up to a 70% combined disability rating. VA’s regulations require the highest disability to be considered first, followed by the lower disabilities in order of severity.
Why Does VA Use This Method?
Each disability rating represents a percentage of the veteran’s remaining ability after the more serious disabilities have already been considered. In other words, the second rating is a percentage of what is left, not another percentage of the original whole.
A simple way to remember it is:
VA does not add each rating to the original 100%. It applies each new rating to the percentage that remains.
This is why two 10% ratings combine to 19% before rounding, rather than simply totaling 20%. It is also why several individual disability ratings may produce a combined evaluation that seems lower than expected.
Another Example
Suppose a veteran has ratings of 60%, 20%, and 10%.
VA starts with the 60% rating, leaving 40% remaining. The 20% rating is applied to that remaining 40%, which adds 8 percentage points. That produces 68%. The 10% rating is then applied to the 32% that remains, adding approximately 3 more percentage points. The resulting combined value is about 71%, which rounds to a 70% combined rating.
Important Note
The calculator provides an estimate based on VA’s combined-rating method. The actual calculation may also be affected by rules such as the bilateral factor for qualifying disabilities involving both arms, both legs, or paired skeletal muscles. Only VA can issue an official combined disability evaluation.