Read CRA Guide RC4064. If parents qualify as your dependents, you may be able to claim their medical expenses, which would include a major part of their nursing home bill. (Line 331) You may also be eligible to claim an amount for infirm dependents over age 18 (Line 306), or transfer a disability amount from the dependent parents (Line 318). It is not clear to me if parents have to claim these first, and you only claim the unused portions, or what. You might want to talk to a tax advisor. You may need some documentation, but people admitted to nursing homes generally have no difficulty qualifying for a Form T2201 - Disability Tax Credit Certificate.