SMC-T is extremely difficult to qualify for.
The regulation 38 CFR 3.350(j) states "The special monthly compensation provided by 38 U.S.C. 1114(t) is payable to
a veteran who, as the result of service-connected disability, is in need of regular aid and attendance for the residuals of traumatic brain injury, is not eligible for compensation under 38 U.S.C. 1114(r)(2), and in the absence of such regular aid and
attendance would require hospitalization, nursing home care, or other residential nstitutional care. Determination of this need is subject to the criteria of 38 CFR 3.352."
Further, 38 CFR 3.352 states: "A veteran is entitled to the higher level aid and attendance allowance authorized by § 3.350(j) in lieu of the regular aid and attendance allowance when all of the following conditions are met:
(i) As a result of service-connected residuals of traumatic brain injury, the veteran meets the requirements for entitlement to the regular aid and attendance allowance in paragraph (a) of this section.
(ii) As a result of service-connected residuals of traumatic brain injury, the veteran needs a “higher level of care” (as defined in paragraph (b)(3) of this section) than is required to establish entitlement to the regular aid and attendance allowance, and in the absence of the provision of such higher level of care the veteran would require hospitalization, nursing home care, or other residential institutional care.
(3) Need for a higher level of care shall be considered to be need for personal health-care services provided on a daily basis in the veteran's home by a person who is licensed to provide such services or who provides such services under the regular supervision of a licensed health-care professional.Personal health-care services include (but are not limited to) such services as physical therapy, administration of injections, placement of indwelling catheters, and the changing of sterile dressings, or like functions which require professional health-care training or the regular supervision of a trained health-care professional to perform. A licensed health-care professional includes (but is not limited to) a doctor of medicine or osteopathy, a registered nurse, a licensed practical nurse, or a physical therapist licensed to practice by a State or political subdivision thereof."
In order to qualify for SMC-T, you may want to first try and get your 40% TBI rating increased to 100%. Then, seek a medical opinion from a doctor who opines that you meet the criteria stated above in the regulations. Best of luck to you!