If you had medical and/or dental expenses for more than one person, then you must determine which expenses belong to each qualifying taxpayer.
Start by totaling all expenses for each qualifying taxpayer. If you have expenses that are for more than one person, such as premiums for a shared insurance policy, split the expenses by the most reasonable method.
A reasonable method for splitting the shared costs of an insurance policy includes splitting the total cost of the policy by the number of individuals covered. For example, divide the premiums for an insurance policy covering two adults by two.
If the number of children covered on an insurance policy does not affect the price of the policy, it's reasonable to count all children on the policy as one individual. For example, divide the premiums for a policy covering two adults and four children by three.