VA Disability Ratings Explained: How “VA Math” Actually Works

If you have a 50% rating and a 30% rating, you might expect an 80% combined rating. VA will give you 70%. The reason is a method veterans call “VA math,” and once you see how it works, your rating letter makes a lot more sense.

Ratings describe the remaining whole person

VA assumes you start as a whole person with 100% “efficiency.” Each disability rating reduces the efficiency that is left, not the original 100%. So after a 50% rating, you are considered 50% efficient. A second, 30% rating applies to that remaining 50%, which is 15 more points of disability. Together, that's 65% — not 80%.

This approach is written into federal regulations at 38 CFR 4.25, which includes the Combined Ratings Table VA uses. The table is simply this calculation done in advance, with results rounded to whole numbers.

The step-by-step method

1. Sort your ratings from highest to lowest.
2. Start with the highest rating.
3. Apply the next rating to what remains: combined = A + B × (100 − A) ÷ 100. Round to a whole number.
4. Repeat for each additional rating, always using the latest combined value as A.
5. Round the final value to the nearest 10 to get your combined rating. A value ending in 5 or higher rounds up.

Worked examples

Notice the last row: adding a 10% rating to a 70% rating doesn't change the combined rating, because 73 rounds down to 70. And the fourth row shows how intermediate rounding matters — 49.6 becomes 50 before the next rating is applied.

Why reaching 100% is hard

Because every new rating applies to a smaller remaining share, combined values approach 100 but rarely get there through combination alone. To be rounded to 100%, the combined value must reach at least 95. Many veterans rated 100% have at least one condition rated 100% on its own, or receive total disability based on individual unemployability (TDIU), which pays at the 100% rate when service-connected conditions prevent substantially gainful employment.

The bilateral factor

There is one adjustment that works in your favor. When disabilities affect both arms, both legs, or paired skeletal muscles, 38 CFR 4.26 applies the bilateral factor:

1. Combine the bilateral ratings with each other using VA math.
2. Add 10% of that combined value (not combined — simply added).
3. Treat the result as a single rating and combine it with your other ratings, highest first.

The regulation's own example uses ratings of 60%, 20%, 10% and 10%, where the two 10% ratings are bilateral. The bilateral pair combines to 19; adding 10% of 19 (1.9) gives 20.9, rounded to 21. The ratings are then applied in order of severity — 60, 21 and 20. Sixty and 21 combine to 68, and 68 and 20 combine to 74, for a 70% combined rating. The bilateral factor doesn't always change the final rating, but when a combined value sits just below a rounding boundary, those extra points can push it into the next 10.

What each combined rating pays

Your combined rating sets your monthly payment. Ratings of 30% and above also add amounts for a spouse, children and dependent parents. Under the rates effective December 1, 2025:

Rounding has real money attached: the step from 60% to 70% for a veteran alone is worth $373.43 a month. See every combination in the 2026 VA disability pay chart.

Does the order of ratings matter?

Mathematically, combining ratings gives almost the same answer in any order, because each step multiplies the remaining efficiency. The small differences come from rounding each intermediate value to a whole number. To keep results consistent, VA always applies ratings from highest to lowest, and the Combined Ratings Table is built that way. When you check your own rating by hand, follow the same order.

What a new rating is worth

Because of rounding, the value of an additional rating depends entirely on where your combined value already sits. A veteran at 70% (from a combined value of 70) who adds a 20% rating moves to 76, which rounds to 80% — an increase of $293.70 a month for a veteran alone. A veteran at 70% whose combined value is 74 gets a bigger push from the same 20%: 74 + 20 × 0.26 = 79.2, which also becomes 80%. But a veteran whose combined value is 65 needs a much larger new rating to reach 80%. That is why two veterans with the same combined rating can see different results from a similar claim.

The same logic applies in reverse. If VA reduces one rating during a review, your combined rating may or may not fall, depending on how close your combined value is to the rounding boundary.

Tips for reading your own rating

• Your decision letter lists each service-connected condition and its individual rating. Enter all of them — including 0% ratings, which don't change the math but still count as service connected.
• Check whether any conditions affect paired limbs; the bilateral factor is applied automatically by VA but is easy to miss when checking by hand.
• A new or increased rating on a small condition may not change your combined rating. Run the numbers before assuming it will.

Sources

• 38 CFR 4.25 — Combined ratings table
• 38 CFR 4.26 — Bilateral factor
• VA.gov — Current veterans disability compensation rates
• VA.gov — About disability ratings

MilPayLab is not affiliated with, endorsed by, or connected to the U.S. Department of Defense, DFAS, DTMO or the Department of Veterans Affairs. Figures are taken from published government rate tables and are provided for information only, not as financial, legal or tax advice. Your finance office, your LES and your VA decision letter are the final word on what you are paid.