The first question in any TDIU claim is arithmetic: does the combination of service-connected ratings meet the thresholds in 38 CFR 4.16(a)? Meeting them does not grant TDIU - it only means the claim is considered on a schedular basis rather than requiring extraschedular referral.
The two schedular paths
Section 4.16(a) describes two ways to reach schedular consideration.
- A single service-connected disability rated 60 percent or more
- Two or more service-connected disabilities with a combined rating of 70 percent or more, at least one of which is rated 40 percent or more
Both paths use combined ratings, not simple addition. The combined ratings table in 38 CFR 4.25 applies each rating to the remaining efficiency, which is why the total is always less than the sum. A 50 percent and a 40 percent combine to 70 percent; two 40 percent ratings combine to 64, which rounds to 60. You can check your own numbers with our combined rating calculator.
When separate ratings count as one disability
The 60 percent single-disability path is broader than it looks, because 4.16(a) directs that certain groups of disabilities be treated as one disability for this purpose:
- Disabilities of one or both upper extremities, or of one or both lower extremities, including the bilateral factor
- Disabilities resulting from a common etiology or a single accident
- Disabilities affecting a single body system, such as orthopedic, digestive, respiratory, cardiovascular, or neuropsychiatric
- Multiple injuries incurred in action
- Multiple disabilities incurred as a prisoner of war
Where veterans start
Every case is different, and there is no obligation at any step. When veterans want to understand what their records actually support, these are the two most common starting points:
- Medical records review
A licensed physician reviews your records for a $250 flat fee and identifies which conditions the available evidence may support. The fee is refunded in full if nothing supportable is identified.
- Nexus letter
When the records support one, a licensed provider writes the medical opinion that addresses the link between your condition and your service or an already service-connected disability.
This matters often. A veteran with several separately rated mental health conditions, or with a back condition rated alongside radiculopathy, may reach the 60 percent single-disability threshold by grouping. Conditions granted on a secondary basis commonly share a common etiology with the primary disability, which is another route into that grouping.
Only service-connected disabilities count
The regulation is explicit that unemployability must result from service-connected disabilities. A non-service-connected condition cannot be used to support the claim, even when it is the most limiting thing in the veteran's life.
That is one practical reason veterans pursue service connection for conditions they had been leaving off their claims. A condition that is currently unrated contributes nothing to TDIU until it is service connected - our guide to what a nexus letter is explains the medical evidence that question usually turns on.
Age and retirement are excluded
Under 38 CFR 4.19, age may not be considered in deciding a service-connected claim, and unemployability due to advancing age or to a non-service-connected disability cannot be the basis for a total rating. A veteran who left the workforce at 67 is judged on the same question as one who left at 37: whether service-connected disabilities prevent substantially gainful work.
Meeting the numbers is not the same as qualifying
Passing the 4.16(a) threshold opens the door. The VA still has to find that the veteran is unable to secure or follow a substantially gainful occupation because of those disabilities. That is where the employment analysis and the medical and vocational evidence do the work.
Veterans who fall short of the percentages are not finished either. Section 4.16(b) exists precisely for that case - see our guide to extraschedular TDIU.
Frequently asked questions
Can two 40 percent ratings qualify for TDIU?
Two 40 percent ratings combine to 64 percent under the combined ratings table, which rounds to 60 and falls short of the 70 percent threshold in 38 CFR 4.16(a). A veteran in that position may still be considered on an extraschedular basis under 4.16(b).
Are several ratings ever counted as one disability?
Yes. Under 38 CFR 4.16(a), disabilities of one or both upper extremities or one or both lower extremities, disabilities resulting from a common etiology or a single accident, disabilities affecting a single body system, multiple injuries in one incident, and multiple disabilities incurred as a prisoner of war are treated as one disability for the threshold test.
Does age count against a TDIU claim?
No. Under 38 CFR 4.19, age may not be used as a factor in evaluating a service-connected disability or in deciding unemployability. The question is whether service-connected disabilities prevent gainful work, not whether the veteran is of retirement age.