Most California public school teachers do not pay into Social Security. They participate in the California State Teachers’ Retirement System (CalSTRS) instead, a state pension that the federal government accepts as a substitute for Social Security coverage. In place of the 6.2% OASDI tax, these teachers contribute roughly 10.2% of their salary to CalSTRS. There are exceptions, and all teachers hired after March 31, 1986 still pay the 1.45% Medicare tax regardless of their Social Security status.
Why CalSTRS Replaces Social Security
California’s Education Code establishes CalSTRS under Part 13 of Title 1 as a Defined Benefit pension program.1Justia. California Code Education Code Part 13 – State Teachers Retirement System Because CalSTRS provides retirement, disability, and survivor benefits that parallel what Social Security offers, members are not required to pay the 6.2% federal OASDI tax on their teaching wages.
What comes out of your check instead is a CalSTRS member contribution. Teachers hired before January 1, 2013, under the “2% at 60” benefit structure pay 10.25% of their creditable earnings. Teachers hired on or after that date, covered by the Public Employees’ Pension Reform Act (PEPRA) and known as “2% at 62” members, pay 10.205%.2CalSTRS. 2025-26 Annual Budget Report The deduction is automatic and goes into the state retirement fund.
When California Teachers Do Pay Social Security
Some California teachers are covered by both CalSTRS and Social Security. The usual reason is a Section 218 Agreement, a voluntary arrangement between a state or local government employer and the Social Security Administration that extends federal Social Security and Medicare coverage to its employees.3Social Security Administration. Section 218 Agreements – State and Local Government Employers These agreements are authorized by Section 218 of the Social Security Act.4Social Security Administration. Social Security Act Section 218 – Voluntary Agreements for Coverage of State and Local Employees Once a district enters one, it is permanent; the district cannot later withdraw its employees from Social Security coverage.
Employment classification matters too. Part-time, substitute, and temporary teachers who do not meet the minimum service requirements for CalSTRS membership may end up in Social Security or an alternative retirement plan instead. The exact rules depend on the district’s policies and collective bargaining agreements.
How to Check Your Own Coverage
The quickest check is your pay stub. Look for an OASDI deduction line. If it shows zero or is missing entirely, you are likely covered only by CalSTRS. For a definitive answer on your district’s Section 218 Agreement status, the SSA recommends contacting California’s designated Social Security Administrator, the official who manages the state’s Section 218 Agreement.3Social Security Administration. Section 218 Agreements – State and Local Government Employers Your district’s HR or payroll office can also tell you which retirement programs apply to your specific position.
Medicare Tax Still Applies
Being exempt from Social Security does not mean being exempt from Medicare. Teachers hired after March 31, 1986 pay the 1.45% Medicare Hospital Insurance tax on their wages, because federal law extended mandatory Medicare coverage to all state and local government employees hired after that date, whether or not they participate in Social Security.5eCFR. 42 CFR 406.15 – Special Provisions Applicable to Medicare Qualified Government Employment Your employer matches that 1.45%, so a total of 2.9% is contributed to Medicare on your earnings.
Teachers hired by their current district before April 1, 1986, with continuous service since, may be exempt from the Medicare tax, but this applies to very few educators still working.
What No Social Security Coverage Means for Medicare at 65
Because many California teachers pay only the Medicare portion of FICA, the credits they build may not be enough to qualify for premium-free Medicare Part A at age 65. Premium-free Part A requires 40 quarters of coverage, which is roughly 10 years of work where FICA taxes were paid.6Centers for Medicare & Medicaid Services. Original Medicare (Part A and B) Eligibility and Enrollment A teacher whose entire career has been in CalSTRS-covered employment, with no earlier job that paid full FICA, may fall short.
If you don’t qualify for premium-free Part A, you can still enroll by paying a monthly premium. In 2026, the full Part A premium is $565 per month for people with fewer than 30 quarters of coverage. Those with 30 to 39 quarters pay a reduced premium of $311 per month.7Centers for Medicare & Medicaid Services. 2026 Medicare Parts A and B Premiums and Deductibles You also have to be enrolled in Medicare Part B to buy into Part A.
Part B has its own late enrollment penalty. If you delay signing up past your initial eligibility window without qualifying for a Special Enrollment Period, your Part B premium increases by 10% for each full 12-month period you were eligible but not enrolled, and that surcharge lasts for as long as you have Part B.8Medicare.gov. Avoid Late Enrollment Penalties For career teachers who may not have enough FICA quarters from other work, planning ahead for these costs matters.
The Social Security Fairness Act and What Changed in 2025
If you have ever been told that your CalSTRS pension would reduce or wipe out any Social Security benefit you had earned elsewhere, that rule no longer applies. Two federal provisions used to do that work: the Windfall Elimination Provision (WEP) reduced retirement benefits from a second career, and the Government Pension Offset (GPO) reduced or eliminated spousal and survivor benefits. Both hit public school teachers especially hard.
The Social Security Fairness Act, signed into law on January 5, 2025, permanently repealed both the WEP and the GPO. The repeal is retroactive to January 2024, meaning neither provision has applied to any benefits payable since that date.9Social Security Administration. Social Security Fairness Act – Windfall Elimination Provision (WEP) and Government Pension Offset (GPO) Update
In practical terms:
- If you earned enough credits from non-teaching work to qualify for Social Security benefits in your own right, your monthly payment is no longer reduced by the WEP formula. You receive the full amount your earnings history produces.
- If your spouse paid into Social Security, any spousal or survivor benefit you are eligible for is no longer reduced by two-thirds of your CalSTRS pension. Teachers whose spousal benefits had been offset to zero now receive the full amount.
- The SSA has already issued more than 3.1 million payments totaling $17 billion to affected beneficiaries, covering increases back to January 2024.9Social Security Administration. Social Security Fairness Act – Windfall Elimination Provision (WEP) and Government Pension Offset (GPO) Update
- If you previously skipped applying for Social Security because WEP or GPO would have erased the benefit, you can apply now. Retroactive benefits for retirement and spousal claims are generally limited to six months before the month you file.
So the short answer stays the same: most California teachers do not pay into Social Security while they are teaching. What has changed is that the pension they build through CalSTRS no longer costs them Social Security benefits they earned somewhere else, or benefits earned by a spouse.