The table below shows the source of contributions to the Social Security and Medicate Trust Funds.

Contributions to the Social Security and Medicare Trust Funds,
by program and source, 2016-2025 (in millions of dollars)
Program and source 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025
Social Security Trust Funds
Old-Age and Survivors Insurance a $710,497 $742,399 $750,371 $839,992 $895,014 $875,387 $992,996 $1,103,842 $1,159,984 $1,187,104
Employer 322,652 336,293 340,901 384,005 408,227 398,575 452,446 503,960 526,175 540,842
Employee 319,940 333,542 338,475 381,121 404,962 395,425 448,042 498,593 521,707 536,095
Self-employed 36,195 36,670 36,489 39,966 42,791 44,235 45,436 51,524 57,705 53,792
General Fund Reimbursement 87 17 18 11 3 1 b b b b
Taxation of benefits 31,623 35,877 34,488 34,890 39,032 37,151 47,071 49,764 54,398 56,374
Disability Insurance a 158,600 169,063 169,719 140,961 146,997 142,826 162,231 179,972 188,399 193,278
Employer 75,347 79,498 80,576 65,906 69,299 67,677 76,842 85,582 89,351 91,779
Employee 74,887 78,854 79,992 65,222 68,747 67,143 76,096 84,671 88,593 90,972
Self-employed 7,157 8,734 8,617 8,249 7,247 7,547 7,740 8,770 9,801 9,138
General Fund Reimbursement 15 3 3 2 b b b b b b
Taxation of benefits 1,194 1,973 530 1,583 1,704 459 1,553 950 654 1,390
Medicare Trust Funds
Hospital Insurance a 279,821 289,164 296,082 312,799 319,017 337,164 390,139 406,808 441,003 449,992
Employer 118,309 121,488 125,025 132,889 141,590 140,885 165,418 170,751 183,986 188,993
Employee 118,309 121,488 125,025 132,889 141,590 140,885 165,418 170,751 183,986 188,993
Self-employed 16,899 18,520 18,232 19,359 20,108 20,773 21,979 25,653 28,478 25,225
Voluntarily enrolledc 3,282 3,463 3,608 3,880 4,034 4,181 4,550 4,685 4,759 5,727
Taxation of benefits 23,022 24,206 24,192 23,781 11,695 30,441 32,775 34,968 39,794 41,054
Supplementary Medical Insurancea, d 72,055 81,522 93,312 99,413 111,200 166,626 130,941 131,166 139,837 150,318
Aged 60,618 69,009 80,041 86,101 97,120 145,994 115,756 117,685 125,427 135,636
Disabled 11,438 12,513 13,271 13,312 14,081 20,632 15,186 13,481 14,410 14,682
a Totals do not necessarily equal the sum of rounded components. Employment taxes depend on tax rates, and, for the Old-Age and Survivors Insurance and Disability Insurance Trust Funds, wage bases (taxable maximums). (Beginning in 1994, no wage base applies to Medicare's Hospital Insurance program.) Employer and employee contributions differ by estimated amounts of employee tax overpayments and by employee tax on tips.
b Between -$500,000 and $500,000.
c Beginning in July 1973, aged ineligibles may voluntarily enroll for Hospital Insurance.
d Includes premiums paid on behalf of eligibles by State governments under "buy-in" arrangements.