You are permanently insured if you are fully insured and you will not lose your fully-insured status when you stop working under covered employment.
Examples include: (1) You have earned the maximum 40 quarters of coverage (QCs), so you are permanently (and fully) insured. (2) You were born in 1949 and worked under covered employment in 1971-77, earning a total of 28 QCs. You attained age 21 in 1970. You were fully insured after you earned 6 QCs and you continued to be fully insured if you were to die or become disabled before the end of 1999 (1998 less 1970 is 28). After 1999 you were no longer fully insured. Because you earned only 28 QCs, you were never permanently insured—Read more at SSA.gov. “Insured Status Requirements.”