Generally, prepaid medical expenses, including dental costs, are not deductible. An old Tax Court case said that advance payment for medical services to be rendered in the following year are not deductible in the year paid. The only exception is for prepaid of lifetime care from a continuing care facility or nursing home.
The IRS action of fixing tax liability that sets in motion collection procedures, such as charging interest, imposing penalties, and, if necessary, seizing property.