There is nothing to file in advance. Claim the deduction on your Idaho income tax return, following the Idaho Individual Income Tax Instructions for the year you are filing.

• You are an Idaho resident filing an Idaho income tax return
• You are 65 years old or older, or you are 62 years old or older and are a wartime veteran with a service-connected disability rating of 10 percent or more, a wartime veteran receiving a non-service-connected disability pension, recognized as disabled by the Social Security Administration, the Railroad Retirement Board or the Office of Management and Budget, or have a permanent disability certified by a physician with no expectation of improvement
• You receive retirement benefits paid by the U.S. Government to a retired service member, or survivor benefits as the unremarried surviving spouse of a retired service member