📝 Executive Summary
Retirees filing jointly can utilize the 0% federal long-term capital gains bracket to reset their cost basis on S&P 500 holdings. By selling and immediately repurchasing shares before December 31, investors can lock in tax-free gains, though this opportunity vanishes annually. The window is narrowing as rising Social Security COLAs and upcoming RMDs at age 73 threaten to push retirees into higher tax brackets.