How the VA Actually Combines Your Disability Ratings (2026 Guide)

If you have ever pulled out a calculator, added 70 + 40 + 10, gotten 120, and assumed the VA owed you a 100% rating, you are not alone. Most veterans encounter this surprise at exactly the wrong moment — usually after a Decision Notice arrives in the mail showing a combined rating much lower than the sum of the individual ones. The good news is that the rule is not arbitrary. It is laid out in plain language in 38 CFR § 4.25, and once you understand the three-step procedure the VA actually uses, the rating you receive on paper will stop feeling like a lottery.

This guide walks through the VA combined rating calculator logic the way a Decision Review Officer would walk through it, with three worked examples drawn from realistic claim profiles.

The short answer

The VA does not add ratings — it combines them by multiplying the remaining whole-person efficiency at each step.

Imagine your body starts at 100% efficiency. The first (and largest) disability eats into that efficiency. Whatever efficiency is left becomes the new baseline against which the next disability is applied. Each successive disability eats into a smaller and smaller pool, which is why veterans with three or four moderate ratings rarely cross the 100% threshold no matter how high the individual numbers look on paper.

The mechanism is sometimes called "VA math" by veterans and by claims agents, but the math itself is just compound interest run in reverse: each disability removes a percentage of what is left, never a percentage of the original 100%.

How the formula actually works

The official procedure under § 4.25 has exactly three steps:

1. Sort your disabilities from highest to lowest rating. Order matters because the formula is sequential and each step affects the next.
2. For each disability in order, multiply the remaining efficiency by (1 − rating). Start with efficiency = 100. After each disability, efficiency becomes efficiency × (1 − d/100).
3. Subtract the final efficiency from 100, then round to the nearest 10%. The VA never publishes ratings of 37% or 64% — every final number is a multiple of 10.

A single illustration makes this concrete. Suppose your service-connected disabilities are 70%, 40%, and 10%, and you assume you will end up at 70 + 40 + 10 = 120%, capped at 100. What actually happens is:

• Start with 100% efficiency.
• After the 70% disability: 100 × (1 − 0.70) = 30% efficiency remaining.
• After the 40% disability: 30 × (1 − 0.40) = 18% efficiency remaining.
• After the 10% disability: 18 × (1 − 0.10) = 16.2% efficiency remaining.
• Combined raw rating: 100 − 16.2 = 83.8%.
• Rounded to nearest 10: 80%.

You can verify the same result by running these numbers through our combined rating calculator. Every step in our calculator's "show the math" panel mirrors the table above.

Why this rule exists

The "compound" formula was not invented to deny benefits. It comes from a 1945 schedule revision designed to model the reality that two disabilities affecting the same person rarely subtract independently from the person's ability to work. A 70% PTSD rating already captures most of the social and occupational impairment the VA is willing to acknowledge in dollars; adding a 10% tinnitus rating on top cannot reasonably push the total to 80% in the same way that two unrelated full-time obligations would. The compounding formula is the VA's way of avoiding double-counting.

The legal authority for this calculation is 38 CFR § 4.25, the official VA Combined Ratings Table. Every VA examiner and every Decision Review Officer is required to use it. When the table appears to give a different answer from the multiplication formula above, it is because the table itself is generated from the formula and rounds intermediate values exactly the way we describe — your handheld arithmetic and the table will agree.

Three real-world examples

To anchor the rule, here are three combinations veterans encounter often.

Example 1 — PTSD plus a back rating. A veteran with a 70% PTSD rating and a 40% lumbar strain combines as follows: 100 × 0.30 × 0.60 = 18. Final efficiency 18%, raw 82%, rounded to 80%. This veteran is one rating away from the 100% schedular threshold, and a 30% sleep apnea claim filed as secondary service connection to PTSD would push the final to 90%.

Example 2 — Three small ratings. Three 10% ratings — for example tinnitus, GERD, and a scar — combine as 100 × 0.90 × 0.90 × 0.90 = 72.9. Raw 27.1%, rounded to 30%. Three 10% ratings do not combine to 30% by addition (which would be exactly 30); they happen to round to 30% because of the rounding rule. If the third rating had been 10% as well, the result would still be 30%, illustrating diminishing returns.

Example 3 — Bilateral knees. A veteran with two 20% knees and 10% tinnitus runs into the bilateral factor, which we cover in detail in its own guide. Briefly, the two knees are combined first (20 → 36), 10% of that is added back (36 + 3.6 = 39.6), and only then is the bundle combined with the tinnitus to arrive at a raw 45.64% — rounded to 50%. Without the bilateral factor the same veteran would have rounded to 40%, illustrating how easily the bonus is missed.

The single biggest source of confusion

The most common mistake veterans make is sorting the wrong way. The formula gives an identical mathematical answer regardless of the order, but only if you carry decimals all the way through. If you round at intermediate steps — which the VA's published table does for display purposes — sorting matters. Always sort highest to lowest, and always preserve at least two decimal places in intermediate calculations. Our calculator does both automatically.

The second-most-common mistake is forgetting that the final rating is rounded to the nearest 10%. A raw combined of 84.9% rounds down to 80%, not up to 90% — because 84.9 is closer to 80 than to 90. A raw of 85.0% rounds up. Veterans who have raw scores in the 84–86 range often spend years pursuing a small additional rating that would push the raw past 85.0% and trigger the round-up. This is the single most leverageable insight in VA-claim strategy, and it is why the bilateral factor and secondary service connection deserve more attention than they usually get.

What to do next

If you are sitting at a Decision Notice trying to understand how the VA arrived at your number, run your individual ratings through the free combined-rating calculator. It mirrors the same § 4.25 formula and shows every line of math, so any discrepancy with your Decision Notice points directly at a specific input. If you are planning a future claim, knowing the formula lets you forecast realistic outcomes before you file.

The combined-rating math is, ultimately, only one piece of the puzzle. The rest of the puzzle — bilateral factor, SMC, TDIU, and secondary connection — multiplies the impact of every individual rating. Read the rest of the field manual to put each of those pieces in the right order.