Can you amortize medical deductions?

You cannot spread it over a few years, you must report medical expenses (remodelling for wheelchair access is considered that) in the year they are paid. 

The are also rules that govern what and how much can be deducted. Per IRS Publication 502, “you can include in medical expenses amounts you pay for special equipment installed in a home or for improvements if their main purpose is medical care for you, your spouse of your dependent.”

If the cost of the improvement does not increase the value of your home, the entire cost of the improvement is entered as your medical expense. (Installing railings, support bars or other modifications to bathrooms generally does not increase the value of your property)

If the cost of the improvement does increase the value of your home, the difference between your cost of the improvement and increase in the value is included as a medical expense. 

To enter Medical expenses in Turbo Tax, please follow the steps below:

1. Federal Taxes tab
2. Deductions and Credits
3. Scroll down to Medical
4. Select Medical Expenses and continue via interview.  Such improvements can be listed as other medical expenses.

To find what other improvements/equipment installations are deductible, and what improvements do not increase the value of the home and can be entered as a full medical expense, see the link below (page 6):

https://www.irs.gov/pub/irs-pdf/p502.pdf