Most veterans assume the VA adds disability ratings together. A 70% rating plus a 30% rating should equal 100%. That seems obvious.
It is also wrong.
The VA uses a formula called the whole person method. It is defined in 38 CFR 4.25. The result of this formula almost always produces a combined rating lower than what simple addition would suggest.
Understanding exactly how VA math works matters. It tells you how close you are to the next rating threshold. It helps you see which condition, if added to your claim, would push your combined rating across a rounding line. It helps you verify that the VA applied your rating correctly.
This page walks through the entire calculation. No assumptions. No guessing. Just the math.
The Core Concept: Remaining Efficiency
The whole person method is built on one idea. You start at 100% functional efficiency. Every disability reduces what remains.
When the VA applies your first and highest-rated condition, it calculates how much of your efficiency that condition takes away. What is left becomes the baseline for the next condition. The second condition then reduces what remains of that baseline. Not the full 100%. The remainder.
This is why two 50% ratings do not add up to 100%. The first 50% reduces your efficiency from 100% to 50%. The second 50% applies to that remaining 50%, taking half of it. That adds 25%. Combined total: 75%. Rounded to nearest 10%: 80%.
The math penalizes veterans with multiple conditions. But it also prevents the impossible result of a rating over 100%.
The Step-by-Step Process
Here is exactly how the VA calculates a combined rating.
Step 1: List all service-connected conditions. Every condition that has been service-connected with a compensable rating goes into the calculation. A 0% rating does not affect the combined percentage. Only compensable ratings (10% and above) count toward the combined rating.
Step 2: Sort from highest to lowest. The VA applies conditions in descending order. The highest rating goes first. The lowest goes last. Order matters because each condition is applied to a shrinking remainder.
Step 3: Apply the bilateral factor if applicable. If you have service-connected conditions affecting both upper extremities or both lower extremities, those conditions are combined first and the bilateral factor is applied to their subtotal. That adjusted subtotal then enters the main calculation as a single number. See the bilateral factor calculator for the full formula.
Step 4: Apply each rating to the remaining efficiency. Starting with the highest rated condition, subtract its rating from 100%. The result is your remaining efficiency. Apply the next condition to that remainder. Subtract the result from the remaining efficiency. Continue until all conditions are applied.
Step 5: Add all the taken efficiency amounts. The combined disability is the sum of all the portions removed from efficiency across each step.
Step 6: Round to the nearest 10%. The raw combined percentage is rounded to the nearest 10% for compensation purposes. A raw combined of 45% through 54% rounds to 50%. A raw combined of 55% through 64% rounds to 60%. This rounding step is where a single percentage point can mean the difference between two rating tiers and hundreds of dollars per month.
A Real Example: Three Conditions
A veteran has three service-connected conditions. PTSD at 70%. Right knee limitation of flexion at 20%. Tinnitus at 10%.
Sort highest to lowest: 70%, 20%, 10%.
Apply PTSD at 70%. Start at 100% efficiency. 70% is taken by PTSD. 30% remains.
Apply knee at 20%. 20% of the remaining 30% = 6%. Running total taken: 76%. Remaining efficiency: 24%.
Apply tinnitus at 10%. 10% of the remaining 24% = 2.4%. Running total taken: 78.4%. Remaining efficiency: 21.6%.
Raw combined: 78.4%.
Round to nearest 10%: 80%.
At 80% with no dependents, the 2026 monthly payment is $1,995.01.
Without tinnitus, the same veteran's raw combined would be 76%. That rounds to 80% as well. Tinnitus did not change the rounded result in this case. But add a fourth condition at 10%, and the raw combined becomes 80.46%, which still rounds to 80%. Add a condition at 20%, and the raw combined jumps to 82.72%, which rounds to 80% still. The next meaningful threshold is 85%, where the combined rounds to 90%.
This is the practical value of understanding VA math. You can see exactly which conditions move the needle and which do not, given your specific starting point.
Why Common Assumptions Are Wrong
"I have 100% but the VA gave me 90%." This is said by veterans who add their individual ratings. A veteran with 70%, 30%, 20%, and 10% does not have 130%. Under VA math, those four ratings combine to approximately 87%, which rounds to 90%. The VA result is correct. Simple addition is not how the system works.
"Adding a 10% condition won't change anything." Sometimes true. Sometimes not. Whether a 10% condition changes your rounded combined rating depends entirely on your current raw combined. If your raw combined is 74%, adding a 10% condition takes you to 76.6%. That rounds to 80%, which is a meaningful increase. If your raw combined is already 76.8%, adding 10% takes you to 79.1%. Still rounds to 80%. Same result. You have to run the actual numbers to know.
"My 100% condition should make my total 100%." A single 100% condition does produce a 100% combined rating. But two conditions, one at 100% and one at 10%, do not combine to more than 100%. The 10% applies to the remaining 0% and adds nothing. This is why veterans rated at 100% schedular do not gain additional compensation from further conditions. The TDIU pathway exists for veterans who cannot reach 100% schedular but are unable to work due to service-connected conditions.
The Rounding Threshold: Where the Real Money Is
The rounding step is the most financially significant part of VA math. Monthly compensation jumps occur at each 10% threshold.
In 2026, the compensation difference between common rating levels with no dependents:
- 70% pays $1,808.45 per month
- 80% pays $1,995.01 per month
- 90% pays $2,241.91 per month
- 100% pays $3,938.58 per month
The gap between 70% and 80% is $186.56 per month. That is $2,238.72 per year. Tax-free.
The gap between 90% and 100% is $1,696.67 per month. That is $20,360 per year. Tax-free.
A veteran sitting at a raw combined of 74% and a rounded rating of 70% needs only 1.1 additional raw points to cross to 75%, where rounding produces 80%. One well-documented secondary condition at 10% can provide that. This is why understanding your raw combined matters as much as knowing your rounded rating.
How to Verify Your Combined Rating
The VA does not always show the intermediate calculation steps in your rating decision. To verify your combined rating:
Take your list of service-connected compensable conditions. Sort them highest to lowest. Work through the steps above. Compare your calculated raw combined to your official combined rating.
If the numbers do not match, check whether the bilateral factor was correctly applied. Check whether all compensable conditions were included. Check whether any conditions were rated at 0% that should have been rated higher.
If you find a discrepancy, a supplemental claim or appeal may be appropriate. A VA-accredited attorney can review your rating decision at no cost.