As per www.canada.ca
“The disability tax credit (DTC) is a non-refundable tax credit that helps persons with disabilities or their supporting persons reduce the amount of income tax they may have to pay. An individual may claim the disability amount once they are eligible for the DTC. This amount includes a supplement for persons under 18 years of age at the end of the year.
The purpose of the DTC is to provide for greater tax equity by allowing some relief for disability costs, since these are unavoidable additional expenses that other taxpayers don’t have to face.