At 65, Medicare eligibility begins with a seven-month enrollment window to avoid penalties. Full Social Security retirement age is 67 for those born in 1960 or later; claiming benefits at 65 reduces monthly payments by about 13.3%. Working at 65 can increase future benefits by replacing lower-earning years. Average benefits at 65 are around $1,607 monthly. Higher income may raise Medicare premiums due to IRMAA surcharges.