How Does VA Math Work? Combined Ratings, Rounding & the Bilateral Factor

Why VA doesn't just add ratings

A rating estimates how much a condition reduces your ability to work and function. VA treats you as a "whole person" who starts at 100% efficient. A 50% disability leaves you 50% efficient. A second disability can only reduce what's left, not the part already counted. If VA simply added ratings, many veterans would pass 100%, which the system doesn't allow outside special programs.

The method, step by step

1. List your ratings from highest to lowest.
2. Take the first rating. Subtract it from 100 to find your remaining efficiency.
3. Apply the next rating to what remains. 30% of a remaining 50 is 15. Add that to your running total.
4. Repeat for every rating. VA's combined ratings table rounds each step to a whole number.
5. Round the final number to the nearest 10. 65 becomes 70. 64 becomes 60.

Example 1: two ratings

Example 2: four ratings

Ratings of 70%, 30%, 20%, and 10%:

Adding these up would give 130. VA math gives 90%.

Example 3: lots of small ratings

Ten separate 10% ratings combine to a value of 65, which rounds to 70%. Each new 10% adds less than the one before because it applies to a smaller remainder. That's why the jump from 90% to 100% is so hard. You need a combined value of 95 or higher, and at that level a new 10% rating adds less than one point.

The bilateral factor

When you have service-connected disabilities in both arms, or in both legs, 38 CFR § 4.26 gives you a small boost:

1. Combine the ratings for the paired limbs first, using VA math.
2. Add (don't combine) 10% of that combined value.
3. Treat the result as a single rating and combine it with your other ratings, from highest to lowest.

Example 4: when the bilateral factor changes your rating

A veteran has PTSD at 50%, sleep apnea at 50%, and both knees at 20%:

Without the bilateral factor, the same ratings combine to 84, which rounds to 80%. For a veteran alone, 90% pays $2,362.30 a month in 2026, compared with $2,102.15 at 80%. That's $260.15 a month more. Our calculator applies the bilateral factor automatically when you mark ratings as left or right arm or leg.

What each combined rating pays

VA's basic monthly rates effective December 1, 2025, for a veteran alone: 10% $180.42 · 20% $356.66 · 30% $552.47 · 40% $795.84 · 50% $1,132.90 · 60% $1,435.02 · 70% $1,808.45 · 80% $2,102.15 · 90% $2,362.30 · 100% $3,938.58. Veterans rated 30% or higher get more for dependents. See the full tables on our 2026 & 2027 VA rates page.

When VA math isn't the whole story

• TDIU can pay at the 100% rate when service-connected conditions keep you from working, even if your combined rating is lower. See TDIU explained.
• Special Monthly Compensation adds payments for certain losses, like SMC-K, or pays above 100%.
• Pyramiding: VA won't rate the same symptoms twice (38 CFR § 4.14). But distinct symptoms, like nerve pain from a back condition, can be rated separately.
• The amputation rule caps the combined rating for an extremity at the level of an amputation at that point.
• Temporary ratings after surgery or hospitalization can briefly pay 100%.

Common VA math mistakes

• Adding ratings. The most common mistake. 40 + 40 + 20 isn't 100. It combines to a value of 71, which rounds to 70%.
• Rounding at every step. VA rounds only the final combined value to the nearest 10. Earlier steps use the whole numbers from VA's combined ratings table, not numbers rounded to tens.
• Applying the bilateral factor to one limb, or to an arm and a leg. It applies only to paired limbs: both arms, both legs, or both arms and both legs. Back and neck ratings aren't part of it.
• Forgetting the order. VA always works from the highest rating to the lowest. Using the table in any other order can give a slightly different answer.
• Assuming 95 means 90. A combined value of 95 rounds up to 100%.

How to check your own decision letter

Your rating decision lists each service-connected condition, its diagnostic code, its percentage, and the effective date. Your "Code Sheet" may also show a bilateral factor when one applies. To check VA's math, list every compensable rating from highest to lowest, mark which ones are left or right arm or leg, and enter them in our calculator. If your result doesn't match VA's combined rating, look for a missed bilateral factor, a rating with a different effective date (combined ratings can change from one date to the next), or a condition VA combined with another one instead of rating it separately. A real math error can be fixed through a Higher-Level Review within one year of the decision.

Ways veterans legitimately raise a combined rating

• Claim secondary conditions caused or worsened by rated conditions.
• Make sure nerve problems such as radiculopathy are rated separately for each limb, which may also trigger the bilateral factor.
• File for an increase when a condition has truly gotten worse. Read Am I underrated? first.
• Check that every rating's effective date is correct.