Installing a home elevator is a major expense, and when it is medically necessary, some of that cost may be deductible. If a doctor recommends a home elevator because a family member has a physical disability that makes using stairs unsafe or impossible, the cost may qualify as a medical expense deduction. Similar to the swimming pool rule, you can deduct the portion of the installation cost that exceeds the increase in your home's value as a result of the improvement. The remaining amount, the part that did add value to your home, is not deductible. You still need to itemize and exceed the 7.5 percent threshold for medical expenses.