Absent a written retraction of the letter ruling, a law or rule change, or a change in the person's particular circumstances that affects the issue being addressed, a letter ruling will be valid for seven years from the date of its issuance. At the end of the 7-year period, the person should review and update the information in his original request for information and re-submit the question to the Department.
35 Miss. Code. R. 1-01-1008