Most veterans assume their disability ratings add up the way normal math works. They don’t.
If you have a 70% rating and a 30% rating, you might assume you’re at 100%. But under VA math, that’s not how combined ratings are calculated.
Understanding how VA math works is critical before you file for a rating increase or assume you’re “close” to the next percentage.
This page breaks down exactly how the VA combines ratings, how the official combined rating table works, and why moving from 90% to 100% is harder than most veterans expect.
What Is VA Math?
“VA Math” is the informal term used to describe how the Department of Veterans Affairs calculates a combined disability rating when a veteran has multiple service-connected conditions.
The VA doesn’t simply add percentages together. Instead, it applies each new rating to the portion of the body that remains “unaffected” after the previous rating is considered.
This method is called the VA combined rating system, and it follows a specific formula laid out in VA regulations.
The result is often surprising.
How the VA Combines Multiple Disability Ratings
The VA uses what is sometimes called the “remaining efficiency” method.
Here’s how it works in simple terms:
- Start with your highest rating.
- Subtract that percentage from 100%.
- Apply the next rating only to what remains.
- Repeat for each additional rating.
- Round the final number to the nearest 10%.
This is why ratings don’t add up normally.
Let’s break it down.
Step-by-Step Examples of VA Math in Action
Example 1: 50% + 50%
- Start with 100%.
- First 50% rating leaves 50% remaining.
- The second 50% applies to the remaining 50%.
- 50% of 50 is 25.
- 50 + 25 = 75%.
- Rounded to 80%.
Example 2: 70% + 30%
- 100% − 70% = 30% remaining.
- 30% of 30% = 9%.
- 70 + 9 = 79%.
- Rounded to 80%.
Example 3: 90% + 10%
- 100% − 90% = 10% remaining.
- 10% of 10% = 1%.
- 90 + 1 = 91%.
- Rounded to 90%.
See your real combined rating in seconds with our VA Disability Calculator
VA Combined Rating Table and Chart Explained
The VA publishes an official combined rating table, sometimes referred to as the VA disability combined rating chart.
The table performs the same calculation shown above, but in grid format. You locate your highest rating on one axis and your next rating on the other, and the table gives you the combined result.
However, many veterans misread the table because:
- It does not add percentages.
- It always applies ratings sequentially.
- The final result is rounded to the nearest 10%.
The table does not change the math. It simply visualizes it.
Whether you use the formula or the official VA combined rating table, the outcome is the same.
Why Small Increases Don’t Always Change Your Final Rating
VA math becomes especially important when considering a rating increase.
If you are already at:
- 80%
- 90%
You have very little “remaining efficiency” left.
That means:
- A 10% increase might add only 1–2 percentage points to your combined total.
- Even a 20% increase might not move you to the next threshold.
This is why many veterans believe they are “close” to 100% when mathematically, they are not.
Understanding this before filing for an increase prevents unrealistic expectations.
Why It’s So Hard to Move from 90% to 100%
This is where VA math becomes most frustrating.
At 90% combined:
- Only 10% of your body is considered “unaffected.”
- Any new rating applies only to that 10%.
So:
- A 10% new rating adds 1%.
- A 30% new rating adds 3%.
- Even a 50% new rating adds only 5%.
To reach 100%, you often need a high new rating, or multiple additional ratings, or a significant increase in an existing major condition.
This is why moving from 90% to 100% is mathematically difficult under the VA combined rating formula.
How to Know If You’re Actually Close to the Next Rating
Because ratings are rounded to the nearest 10%, your true number matters.
For example:
- 84% rounds down to 80%.
- 85% rounds up to 90%.
That 1% difference can determine whether an increase moves your combined rating at all.
Before filing for an increase, it’s critical to calculate:
- Your current true combined percentage (not just the rounded one).
- How much a potential increase would realistically add.
- Whether that increase would cross the next rounding threshold.
Without that math, you may pursue an increase that does not change your compensation.
Should You File for a Rating Increase Based on VA Math?
VA math is meant to clarify your next move, not shut the door on it. If your condition has clearly worsened or you qualify for a significantly higher percentage, an increase may absolutely be worth pursuing. And if you’re close to the next rounding threshold, even a modest change could move your combined rating.
At the same time, not every increase shifts the final number. Understanding how your ratings combine allows you to make a smarter, more confident decision about what to do next.
The goal isn’t just to file, it’s to file when it actually improves your outcome.
FAQs About VA Math
Does the order of my disability ratings affect my combined rating?
No. The VA always applies ratings from highest to lowest automatically when calculating your combined rating. You cannot rearrange percentages to get a higher result. The final outcome will be the same regardless of the order in which conditions were granted.
Can bilateral factors change my combined VA rating?
Yes. If you have disabilities affecting both arms, both legs, or paired skeletal muscles, the VA may apply a bilateral factor before calculating your final combined rating. This can slightly increase your total percentage and may help you cross a rounding threshold in certain cases.
Does adding a new secondary condition increase my combined rating more than raising an existing one?
Sometimes. Because of how VA math works, adding a secondary condition with a meaningful percentage can have a larger impact than increasing an existing rating by 10%. The actual effect depends on your current combined percentage and how much “remaining efficiency” you have left.
If my combined rating doesn’t change, does an increase still matter?
It can. Even if your overall combined percentage stays the same, a higher individual rating may affect eligibility for other benefits, special monthly compensation, or future claims. The strategic value of an increase is not limited to the combined number alone.
Can VA math ever be corrected if it was calculated incorrectly?
Yes. If the VA misapplies the combined rating formula, fails to apply the bilateral factor, or rounds incorrectly, that error can be challenged through the appropriate review process. While rare, math errors do occur and can impact compensation.