VA combined rating math: why 50% + 30% is not 80%
The VA does not add your ratings. It stacks them against whatever is left of you, which is why the fourth condition is worth far less than the first, and why your combined rating always lands lower than you expect.
A veteran with a 50% rating and a 30% rating does not have an 80% combined rating. They have 70%. Nothing was taken from them and no one made a mistake. That is simply how 38 CFR § 4.25 works.
Understanding the arithmetic changes how you spend your effort. It tells you which conditions are worth pursuing, why chasing a fourth 10% rating is usually a waste of a year, and where the real jumps in monthly compensation actually sit.
The whole-person model
The VA treats you as starting at 100% efficient. Each disability takes a percentage of what remains, not a percentage of the original hundred.
So a 50% rating leaves you 50% efficient. The next rating, 30%, is applied to that remaining 50, not to the full 100:
| Step | Calculation | Running total | Efficiency left |
|---|---|---|---|
| Start | — | 0% | 100% |
| Apply 50% | 50% of 100 = 50 | 50% | 50% |
| Apply 30% | 30% of 50 = 15 | 65% | 35% |
65 is the combined value. That whole number is what the VA's combined ratings table holds at this step, and it is what gets carried into the next combination. Only after every rating has been combined does the VA round the final value to the nearest 10: 65 rounds up to 70%.
Order your ratings highest to lowest, then repeatedly: take the percentage of what is left, add it to the running total, round that total to a whole number, and subtract it from what is left. Round to the nearest 10 once, at the very end. The whole-number step is not optional: it is how the VA's table works, and skipping it can land you a full 10-point step below what the VA will actually pay.
A three-condition example
Say you are rated 50% for a mental health condition, 30% for migraines, and 20% for a back condition.
| Rating | Applied to | Adds | Running total | Efficiency left |
|---|---|---|---|---|
| 50% | 100 | 50 | 50 | 50 |
| 30% | 50 | 15 | 65 | 35 |
| 20% | 35 | 7 | 72 | 28 |
Combined value 72 → rounds down to 70%. Note what happened: the 20% rating added seven points and did not move the final number at all. If instead the third condition had been rated 30%, it would have added 10.5 points, which the table holds as 76, and 76 → 80%. The gap between a 20% and a 30% rating on that third condition is an entire 10-point step in compensation.
Why the order is highest-first
Because every step is rounded to a whole number, the order you combine in can change the result by a point, and a point is sometimes the difference between rounding down and rounding up. That is why the regulation does not leave the order to you: 38 CFR 4.25 says the disabilities are arranged in the exact order of their severity, highest first, and this calculator sorts them that way before it starts. Follow the same order by hand and you will always land on the VA's number.
The bilateral factor
If you have disabilities affecting paired extremities, both arms, both legs, or paired skeletal muscles, 38 CFR § 4.26 adds a bonus. The bilateral conditions are combined with each other first, then 10% of that combined value is added, and only then is the result combined with everything else.
Example: 20% right knee, 10% left knee, 30% for an unrelated condition.
| Step | Calculation | Value |
|---|---|---|
| Combine the bilateral pair | 20, then 10% of the remaining 80 = 8 | 28 |
| Add the bilateral factor | 10% of 28 = 2.8, so 30.8, which the table holds as | 31 |
| Combine with the 30% | 31 first (it is the larger), then 30% of the remaining 69 = 20.7, so 51.7, which the table holds as | 52 |
| Round | nearest 10 | 50% |
Without the bilateral factor the same conditions combine to 50 (30, then 44, then 49.6 held as 50), which also rounds to 50, a reminder that the factor helps at some values and disappears into rounding at others. It matters most when you are sitting near a boundary.
Why the last 10% is so hard
Look at what each additional 10% rating is worth as your combined value climbs:
| Already at | A new 10% rating adds |
|---|---|
| 0% | 10.0 points |
| 50% | 5.0 points |
| 70% | 3.0 points |
| 90% | 1.0 point |
At 90% combined, three separate 10% grants add up to roughly 2.9 points. That is why veterans get stuck at 90% for years: reaching 100% schedular from there effectively requires a single large rating, not a pile of small ones.
The route to being paid at the 100% rate is often not another small rating. It is either an increase on a condition that is already rated but under-rated, or Total Disability based on Individual Unemployability, which pays at the 100% rate without a 100% schedular rating. See the TDIU guide.
Rounding: the last step, and only the last step
Two rules that trip people up:
- Round once. The intermediate values are carried unrounded. If you round after each combination you will drift away from the VA's number.
- Round to the nearest 10, with 5 going up. 64 → 60. 65 → 70. 74 → 70. 75 → 80.
This is why the exact combined value matters even though your award letter shows a round number. Sitting at 74 means a single small grant can push you to 80; sitting at 71 means it probably cannot.
What the combined rating does and does not decide
The combined percentage sets your basic monthly compensation rate, and dependents (spouse, children, dependent parents) increase that rate at 30% and above. But several things run on their own rules and are decided separately:
- Special Monthly Compensation is paid on top of the schedule for specific losses, not derived from the combined percentage.
- TDIU pays at the 100% rate based on employability, with its own percentage thresholds under § 4.16.
- Permanent and Total status affects future exams and dependent benefits, and is a separate determination from reaching 100%.
- Ancillary benefits, healthcare priority, state benefits, property tax exemptions, commissary access, each have their own thresholds, and several state benefits key off 100% or P&T specifically.
A note on pyramiding
You cannot be rated twice for the same symptom under two different diagnostic codes, § 4.14 prohibits it. What you can do is claim genuinely distinct manifestations separately: a back condition rated on limitation of motion and a separate radiculopathy rated on the nerve, for example, are different disabilities with different criteria. Knowing the difference keeps a claim from being denied as duplicative while still capturing everything you are entitled to.
READY214 has a free combined-rating calculator with the bilateral factor built in, plus a condition library showing what each rating level actually requires. No account needed.