A letter of medical necessity (LMN) is a letter written by your doctor that verifies the services or items you are purchasing are for the diagnosis, treatment, or prevention of a disease or medical condition. This letter is required by the IRS for certain eligible expenses. Review the list of eligible expenses to see if you need a letter of medical necessity for a particular type of expense. Each country will have its own format and requirements so please review your specific country requirements. If you need assistance please let us know.