The VA generally refers to a claim as a TDIU claim when two conditions are met: 1) a veteran has one service-connected disability with a 60% or more disability rating, or has two or more service-connected disabilities with a combined rating of 70% or more, and 2) there is medical evidence of unemployability. If the veteran satisfies these two conditions, then he will be entitled to a 100% disability rating, even though he does not satisfy that 100% disability rating under the schedule. See 38 C.F.R. §4.16(a)
An extra-schedular rating, on the other hand, applies to veterans who are unemployable due to their service-connected disability(ies), but whose disability(ies) does not meet the percentage requirements under §4.16(a). See 38 C.F.R. §4.16(b.)
A veteran can be rated 100% disabled under both a TDIU or extra-schedular theory. See Bowling v. Principi, 15 Vet.App. 1, 5-9 (2001).
