Social Security is funded primarily by a payroll tax (FICA) split between employee and employer. Earnings above an annually adjusted wage base are not taxed for Social Security, though Medicare taxes apply to all wages. As a result, a worker earning many times the cap pays the same Social Security tax as one earning at the cap.
The program's trustees project the combined trust funds will be unable to pay scheduled benefits in full within roughly the next decade absent congressional action. Raising or eliminating the cap is one of several levers — alongside benefit changes, retirement-age adjustments, and rate changes — that lawmakers have considered.
Proposals range from lifting the cap entirely on all earnings, to applying the tax above a high "donut hole" threshold, to indexing the cap more aggressively. Each option has different implications for the program's solvency, for benefit calculations, and for high earners' tax burden.