If you are considered to have provided more than half of a qualifying relative's support under a multiple support agreement, you can include medical expenses you pay for that person. A multiple support agreement is used when two or more people provide more than half of a person's support, but no one alone provides more than half. Any medical expenses paid by others who joined you in the agreement cannot be included as medical expenses by anyone. However, you can include the entire unreimbursed amount you paid for medical expenses.

This information is found in Publication 502, Medical and Dental Expenses.