Why do I need a Statement of Permanent and Total Disability and what is it?

 If you got a physician's statement in an earlier year and, due to your continued disabled condition, you were unable to engage in any substantial gainful activity during the tax year, you may not need to get another physician's statement for the tax year. For a detailed explanation of the conditions you must meet, see the instructions for Part II of Schedule R (Form 1040) or Schedule 3 (Form 1040). If you meet the required conditions, check the box on line 2 of Part II of Schedule R (Form 1040) or Schedule 3 (Form 1040).

 The credit is based on your filing status, age, and income.
If you are married and filing a joint return, it is also based on your spouse's age and income. You may be able to take this credit if either of the following
applies.
1. You were age 65 or older at the end of the tax year, or
2. You were under age 65 at the end of the tax year and you meet all of the following.
a. You were permanently and totally disabled on the date you retired. If you retired before 1977, you must have been permanently and totally disabled on January 1, 1976, or January 1, 1977.
b. You received taxable disability income for the current tax year.
c. On January 1, of the current tax year, you had not reached mandatory retirement age (the age when your employer's retirement program would have required you to retire).