About Aphthous Ulcer: These small sensitive painful craters in the mouth are common canker sores. There are many possible causes of apthous ulcers and frequently the cause is unknown. See also: sub-topics
The IRS phone number for individuals is (800) 829-1040. Businesses can call (800) 829-4933. Hearing impaired individuals can contact the IRS using TDD at (800) 829-4059. Operating hours are between 7 a.m. and 10 p.m. in your local time zone. After hours, a recording will direct you. Have all your paperwork in front of you when you call.
Office Hours: Office hours are from 8:00 a.m. to 4:00 p.m. (Eastern Standard Time, year round), Monday through Friday. The office is closed from Noon to 1:00 p.m., and on all county holidays.