VA Disability Combined Ratings Explained

Why 30% + 20% doesn't equal 50% in VA math

By MilMath Team · Updated June 2026

One of the most common surprises veterans run into is opening a VA rating decision and finding that two disabilities rated 30% and 20% added up to a combined 40% — not the 50% they expected. This is not a mistake, and it is not the VA shorting you. It is the result of a specific method called combined ratings, sometimes nicknamed "VA math." Once you understand the logic, the numbers stop feeling random and start making sense.

This guide walks through how combined ratings actually work: the "whole person" idea behind them, how to read the combined ratings table, when the bilateral factor applies, and how the final rounding step decides your real percentage. For the live monthly dollar amounts tied to each rating, always confirm with VA.gov, because those rates change with annual cost-of-living adjustments.

The Whole Person Concept

The VA's method is rooted in the idea that a healthy person starts at 100% efficiency — fully able-bodied. Each service-connected disability reduces that efficiency, but here is the key: each new disability is applied to what is left, not to the original 100%.

Think of it like spending from a shrinking account. Your first disability takes its share of the whole. The second disability can only take its share of whatever remains. Because you cannot be more than 100% disabled, the percentages have to compound rather than stack. This is why several mid-range ratings often combine to less than their simple sum.

Why Ratings Are Not Added

If the VA simply added ratings, a veteran with five 25% disabilities would reach 125%, which is meaningless. The whole-person model prevents that by always working against remaining ability. The practical effects are worth knowing:

• Higher ratings carry more weight. Adding a 10% disability to an existing 80% does far less than adding it to an existing 20%, because there is less "remaining ability" for it to act on.
• Order does not matter for the math, but the table assumes you start with the largest. The VA lists your disabilities from highest to lowest and combines them in that order.
• Small ratings can get "absorbed." Once you are at a high combined rating, a minor additional condition may not move your final number at all after rounding.

How to Read the Combined Ratings Table

The official tool is the Combined Ratings Table in 38 CFR § 4.25. It is a grid: you find your largest rating along one axis and your next rating along the other, and the cell where they meet is the combined value. You then take that result and combine it with your next-largest disability, and so on, two numbers at a time.

You do not have to memorize the table. The math underneath it is straightforward, and you can reproduce any cell with simple arithmetic, shown below. Our VA Combined Rating Calculator applies the table for you and handles the ordering automatically.

A Worked Example

Example: Suppose you have two service-connected conditions:

• 30% for a back condition
• 20% for a knee condition

Here is the step-by-step calculation, exactly mirroring the table:

1. Start with your largest rating: 30%. That means you are considered 70% able-bodied.
2. Apply the 20% knee disability to the remaining 70%: 20% of 70 = 14.
3. Add that to your starting figure: 30 + 14 = 44%.
4. Round to the nearest 10%: 40% combined rating.

So 30% and 20% combine to 40%, not 50%. If you then added a third disability — say 10% — you would apply it to the remaining 56% (100 minus 44), giving 5.6, for a new pre-rounding total of about 49.6%, which rounds to 50%.

The Bilateral Factor

The VA recognizes that losing function on both sides of the body — both arms, both legs, or paired skeletal structures — is more disabling than the same problem on one side, because it limits how you compensate. When you have disabilities affecting both extremities, the VA adds a bilateral factor.

The mechanics: the VA first combines the disabilities of the paired limbs, then adds an extra 10% of that combined value, and only then combines the result with your other (non-bilateral) ratings. Importantly, the bilateral factor is calculated before the final rounding step.

Example: If a right-knee condition and a left-knee condition combine to 30%, the bilateral factor adds 10% of 30 = 3, raising that group to 33% before it is folded in with everything else. It is a modest bump, but on borderline cases it can be the difference between rounding down and rounding up.

How VA Rounding Works

After all combining and any bilateral factor, the VA rounds to the nearest whole 10%. The rule is simple but consequential:

• A pre-rounding figure ending in 1 through 4 rounds down (44 becomes 40).
• A figure ending in 5 through 9 rounds up (45 becomes 50).

This is why veterans near a threshold care so much about a single point. A combined 44 rounds to 40, while a 45 rounds to 50 — and the jump from 40% to 50% can mean a meaningful difference in monthly compensation and, for some, eligibility considerations. It also explains why adding a small disability sometimes changes nothing: if you were already at, say, 81%, a tiny addition may still round back to 80%.

Why This Matters for Your Compensation

Your combined rating, not your individual ratings, determines your monthly tax-free compensation and can affect access to other benefits. Because the dollar figures are adjusted annually and vary with dependents, we will not quote a fixed table here.

Example (illustrative only): Suppose a veteran with no dependents moves from a 40% to a 50% combined rating. The monthly payment difference between those two tiers is substantial — often several hundred dollars per month — which is why the rounding line is worth understanding. For the exact current amounts based on your rating and dependents, check the official rate tables at VA.gov.

Frequently Asked Questions

Why is my combined rating lower than the sum of my ratings?
Because each disability is applied to your remaining ability, not the full 100%. Percentages compound rather than add, so the combined total is almost always less than a straight sum once you have more than one rating.

Does the order of my disabilities change the result?
The VA combines from highest to lowest, but the final combined number is the same regardless of order. The largest-first convention just matches how the official table is laid out.

When does the bilateral factor apply?
Only when you have disabilities affecting both of a paired set of extremities — for example both knees or both arms. The VA combines those paired conditions, adds 10% of that result, then combines with your remaining ratings before rounding.

How does rounding decide my final percentage?
After all combining, the VA rounds to the nearest 10%. Endings of 1–4 round down and 5–9 round up, so a pre-rounding 44% becomes 40% and a 45% becomes 50%.

Use Our Calculator

Rather than work the table by hand, let our VA Combined Rating Calculator do the math for you — it orders your disabilities, applies the bilateral factor, and rounds the final result.

This article is for educational purposes only and is not official VA guidance. Combined ratings and compensation amounts change; always verify your specific situation with the authoritative sources at VA.gov or with a VA-accredited representative.