How VA math works

"VA math" is the name veterans give to the combining method in 38 CFR 4.25. It feels wrong the first time you see it, because it is built on a different idea than addition: you are a whole person who starts 100% efficient, and each disability removes its percentage of the efficiency that remains.

The method, step by step

• Arrange every rating from highest to lowest. Order matters for the steps, though the table is built so the result comes out the same.
• Start with the highest rating. A 60% rating means you are 40% efficient.
• Apply the next rating to the remaining efficiency: 30% of 40 is 12, so 60% and 30% combine to 72.
• Repeat, rounding each step to a whole number (the published table only holds whole numbers; halves round up).
• Only at the very end, round the combined value to the nearest multiple of 10, with a final 5 rounding up. 65 becomes 70; 52 becomes 50.

Why your ratings "add up" to less

Three ratings of 50%, 30%, and 20% add to 100 but combine to 72: 50 leaves 50, 30% of 50 is 15 (running value 65), 20% of the remaining 35 is 7 (combined value 72, a 70% rating). Nobody's arithmetic is broken; the second and third conditions can only disable the part of you the earlier ones left working. That is also why reaching 100% by combining is so hard: a combined value of 95 is required, and each added rating moves the value by a percentage of a shrinking remainder. (A single condition rated 100%, or a 100% rating granted another way such as TDIU, is a separate path.)

The points that decide ratings

Because the final rounding happens at 5, the combined values that matter are 5, 15, 25, and so on up to 95. A combined value of 74 pays at 70%; 75 pays at 80%. The calculator shows how many points of combined value you are from the next threshold, which is the honest way to see what one more rated condition, or one increase, would have to contribute.

Common mistakes

• Adding the percentages. The single most common error, and the reason this site exists.
• Rounding in the middle. VA rounds each combining step to a whole number (that is what the table does) but converts to a multiple of 10 only once, after every disability is combined.
• Forgetting the bilateral factor. Paired arms, legs, and muscles get their 10% addition before the main combining; see the bilateral factor page.
• Counting 0% ratings. A 0% (non-compensable) rating is service-connected but adds nothing to the combined value. Keep the paperwork anyway: a 0% today is the established connection an increase builds on later.

Run your own numbers in the calculator, or look values up in the combined ratings table.