If you have a 50% rating and a 30% rating, you'd expect 80%. The VA says 70%. That's not a mistake — it's "VA math," and once you see how it works, it stops feeling like a trick.
The VA never adds your ratings
The rule comes from 38 CFR §4.25, the Combined Ratings Table. Instead of adding percentages, the VA measures how much healthy, working ability you have left — your remaining efficiency — and applies each new disability only to what remains.
So your most severe disability takes its bite first. The next disability can only take a bite out of what's still left, not the whole.
A worked example: 50% and 30%
- Start with your highest rating: 50%. You are now considered 50% disabled, with 50% ability remaining.
- Apply the 30% rating to that remaining 50%: 30% × 50 = 15 points.
- Add it on: 50 + 15 = 65.
- Round to the nearest 10%: 70%.
So 50% and 30% combine to a 65 value, which the VA pays at 70%. Not 80%.
Adding a third rating
You keep going the same way, highest to lowest. Say you also have a 20% rating — apply it to the remaining efficiency of the running value (65 from above):
- Remaining after 65 is 35. Apply 20%: 20% × 35 = 7 points.
- 65 + 7 = 72.
- Round to the nearest 10% → 70%.
So 50% + 30% + 20% still comes out to 70%. Three disabilities, and the overall rating didn't even move to 80%. This is the single most common surprise veterans run into.
Here's the same procedure, step by step, for 50% + 40% + 20%:
| Step | Working | Running value |
|---|---|---|
| Start with 50% | Highest rating goes first | 50 |
| Apply the 40% | 40% × remaining 50 = 20 | 50 + 20 = 70 |
| Apply the 20% | 20% × remaining 30 = 6 | 70 + 6 = 76 |
| Round once, at the end | 76 → nearest 10 | 80% |
The rounding rule matters more than you think
After combining everything, the VA rounds the result — once, at the very end — to the nearest 10%:
- A combined value of 64 rounds down to 60%.
- A combined value of 65 rounds up to 70%.
That single point is worth real money. In 2026, 60% pays $1,435.02 a month for a veteran alone and 70% pays $1,808.45 — a difference of $373.43 every month ($4,481.16 a year) riding on one point of combined value. It's why even a small new rating can raise your whole level: at a 64 value, the right 10% claim moves you to 70%. Full amounts are on the 2026 pay chart.
More combinations, worked and verified
Every row follows the same §4.25 procedure: order high to low, apply each rating to the remaining efficiency, round once at the end.
| Ratings | Combined value | Rating paid |
|---|---|---|
| 10 + 10 | 10 + (10% × 90) = 19 | 20% |
| 10 + 10 + 10 | 19 + (10% × 81) = 27.1 | 30% |
| 50 + 30 | 50 + (30% × 50) = 65 | 70% |
| 40 + 40 + 20 | 64 + (20% × 36) = 71.2 | 70% |
| 50 + 50 | 50 + (50% × 50) = 75 | 80% |
| 50 + 40 + 20 | 70 + (20% × 30) = 76 | 80% |
| 90 + 10 | 90 + (10% × 10) = 91 | 90% |
The same 10% rating is worth 9 points on its own but a single point on top of a 90 — the whole character of VA math in one column.
Why two ratings can never reach 100%
Because each rating only chips away at what's left, you get diminishing returns. Two 50% ratings combine to 75 (50, then 50% of the remaining 50 = 25 more), which rounds to 80% — not 100%. A schedular 100% requires a combined value of 95 or higher — why the jump from 90% to 100% is the hardest step in the system, and why TDIU exists as a separate path to 100%-level pay for veterans who can't work.
The shortcut the VA uses
Internally the math is just multiplying the "remaining efficiency" each time: a 50% and 30% disability leave you 0.50 × 0.70 = 0.35 (35%) efficient, i.e. 65% disabled — the same 65 as above. The Combined Ratings Table in §4.25 pre-computes this so adjudicators don't have to.
The bilateral factor is applied first
One wrinkle in the order of operations: if compensable disabilities affect both arms or both legs, 38 CFR §4.26 combines those paired ratings first, adds 10% of that value, and rounds to the nearest whole number — and that single number enters the overall combination as one rating. Two 20% knees combine to 36; adding 3.6 gives 39.6, treated as a single 40. The bilateral factor guide covers the full procedure and who qualifies.
The plateau near the top
The higher your combined value climbs, the less each new rating is worth. At a combined value of 90, only 10 points of efficiency remain, so a new 10% rating adds exactly one point: 90 + 1 = 91, which still rounds to 90%. If you're in that zone, what matters is your exact combined value and which claims are big enough to move it — the subject of the 90% to 100% guide.
Once a rating is in place, protections build
Two long-run rules, briefly. Under 38 CFR §3.951(b), a rating continuously in effect for 20 years generally cannot be reduced below the lowest level it held in that period, except for fraud. And under 38 CFR §3.957, service connection itself generally cannot be severed once in place for 10 years, again absent fraud. The first guards the percentage; the second guards the connection.
What this means for you
Two takeaways. Never assume your ratings add up — combine them the VA way (or let the calculator do it) before you count on a number. And because of rounding, small conditions matter a lot near a 5-point threshold and very little far from one; your exact combined value tells you which case you're in.
Frequently asked questions
Why is my combined rating lower than the sum of my ratings?
Because 38 CFR §4.25 combines ratings instead of adding them. Each rating applies only to the ability the previous ratings left behind, so 50% and 30% combine to 65 — paid as 70%, not 80%.
How does the rounding rule work?
The combined value is rounded once, at the end, to the nearest 10 — 1–4 down, 5–9 up. So 64 pays as 60% while 65 pays as 70%, a one-point difference worth $373.43 a month in 2026.
Can two 50% ratings ever make 100%?
No. They combine to 75, which pays as 80%. A schedular 100% requires a combined value of 95 or higher — several high ratings, not two moderate ones.
Can adding a new rating ever lower my combined rating?
No — a new rating can only raise the combined value or leave the rounded rating where it was. Long-held ratings also gain protection: 20 years protects the percentage (§3.951(b)), and 10 years protects service connection itself (§3.957), except for fraud.
When does the bilateral factor apply?
When compensable disabilities affect both arms or both legs (or paired skeletal muscles). Those ratings combine first and get 10% added — two 20% knees become 36 + 3.6 = 39.6, treated as a single 40 — before everything else.