To qualify for this credit, you must be aged 65 or older OR retired on permanent and total disability and received taxable disability income for the tax year; AND with an adjusted gross income OR the total of nontaxable Social Security, pensions annuities or disability income under specific limits.
According to the IRS, you have a permanent and total disability if you can't engage in any substantial gainful activity because of your physical or mental condition. A qualified physician must certify that the condition has lasted or can be expected to last continuously for 12 months or more, or that the condition can be expected to result in death. If you are under age 65,
you must have a physician’s statement, which certifies that you had a permanent and total disability on the date you retired. This statement does not need to be filed with the return but must be kept with your tax records.