Whether substitute teachers pay into Social Security depends almost entirely on where they work. Substitutes at private schools, parochial schools, and most charter schools have the standard 6.2% Social Security tax withheld from every paycheck. Many public school substitutes do not, because their district opted out of Social Security decades ago under a federal agreement and enrolled its part-time staff in a replacement retirement plan instead. Your pay stub will tell you which category you’re in.
Why Public School Substitutes Are Treated Differently
Public school districts don’t follow the same payroll rules as private employers. They operate under Section 218 of the Social Security Act, which lets state and local governments enter voluntary agreements with the Social Security Administration to bring their employees into the federal system.1Social Security Administration. Section 218 Agreements – State and Local Government Employers Where no agreement exists, or where the agreement specifically excludes a position, workers in that position don’t pay Social Security tax and don’t earn Social Security credits for that work.
These agreements cover positions, not people. If the substitute teacher slot in a district is covered, everyone filling it pays in. If it’s excluded, nobody filling it does, no matter how long they stay.1Social Security Administration. Section 218 Agreements – State and Local Government Employers Part-time positions are one of the categories states can optionally exclude, and substitute teaching slots frequently fall into that bucket.2Internal Revenue Service. State and Local Government Employees Social Security and Medicare Coverage
Section 218 agreements became irrevocable in 1983.3Social Security Administration. Introduction to State and Local Coverage Once a district opted in or out, it stayed that way. So a substitute might pay into Social Security in one district and owe nothing the next town over, because the two districts made different choices in the 1950s or 1960s. Each state has a State Social Security Administrator who maintains the agreement and can confirm coverage for a specific position.4Social Security Administration. State Social Security Administrator
Medicare Comes Out Either Way
Even substitutes in Section 218-exempt positions almost always pay the 1.45% Medicare tax. Federal law requires all state and local government employees hired after March 31, 1986, to pay Medicare regardless of whether their position is covered for Social Security.5eCFR. 42 CFR 406.15 Special Provisions Applicable to Medicare Qualified Government Employment The employer matches that 1.45%.
A narrow exception exists for workers continuously employed by the same government entity since before April 1, 1986, and enrolled in a public retirement system.6Internal Revenue Service. Medicare Continuing Employment Exception In practice, almost no current substitute qualifies, since it requires nearly 40 years of unbroken service with one employer.
What Replaces Social Security When Your District Opted Out
Public school employees who aren’t covered by a Section 218 agreement must be enrolled in a qualifying public retirement system, often called a FICA replacement plan.2Internal Revenue Service. State and Local Government Employees Social Security and Medicare Coverage That requirement has been in place since July 1991.
For defined contribution plans, federal regulations require a minimum allocation of at least 7.5% of the employee’s compensation. The contribution can come from the employer, the employee, or a combination.7eCFR. 26 CFR 31.3121(b)(7)-2 – Service by Employees Who Are Not Members of a Public Retirement System Many districts fund it entirely through mandatory employee payroll deductions, which is why a substitute may see a 7.5% retirement line on a pay stub where the Social Security line would otherwise be. The money goes into a 401(a) or 403(b) account. For part-time, seasonal, and temporary employees, the benefit must be 100% nonforfeitable, so you keep it if you leave.
After separating from the district, you can typically roll the balance into an IRA or another eligible retirement plan without the 10% early withdrawal penalty. A lump-sum cash distribution is usually available about 30 days after separation, but taking cash triggers income tax and the early withdrawal penalty if you’re under 59½.
How This Affects Your Social Security Credits
Social Security retirement benefits require 40 credits, roughly ten years of covered work.8Social Security Administration. Social Security Credits You can earn up to four credits per year. In 2026, each credit takes $1,890 in covered earnings, so $7,560 in covered wages maxes you out for the year.9Social Security Administration. Quarter of Coverage
Only covered wages count. A substitute who earns $15,000 in a year but whose $10,000 of it came from a non-covered district only builds credits on the remaining $5,000. Over a career of moving between districts, that piecemeal accumulation can leave you short of 40 credits and locked out of Social Security retirement benefits entirely.
The WEP and GPO Repeal Changed the Math for Split Careers
For decades, two provisions cut Social Security benefits for workers with a foot in each system. The Windfall Elimination Provision reduced retirement benefits for anyone who also received a pension from non-covered work. The Government Pension Offset cut spousal and survivor benefits by two-thirds of the worker’s government pension.10Social Security Administration. Windfall Elimination Provision Substitute teachers with both a small FICA replacement balance and modest covered earnings often got hit by them.
The Social Security Fairness Act, signed on January 5, 2025, eliminated both provisions for benefits payable after December 2023.10Social Security Administration. Windfall Elimination Provision A substitute with some covered years and some non-covered years no longer sees a reduced Social Security check because of the non-covered pension. If your benefits were previously reduced under either rule, the SSA is recalculating payments automatically.
One holdover: employers must still give new hires Form SSA-1945, which describes the effect of non-covered employment on Social Security benefits.11Social Security Administration. State and Local Government Employers Information The form requirement wasn’t repealed alongside WEP and GPO, so you may still receive it starting a non-covered position even though the penalties it warns about no longer apply.
Private Schools, Parochial Schools, and Most Charter Schools
Substitute teachers at private, parochial, and most charter schools pay Social Security and Medicare like any other private-sector employee. The employer withholds 6.2% for Social Security and 1.45% for Medicare, then matches both, sending a combined 15.3% to the IRS.12Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates Section 218 opt-outs are only available to state and local government entities, so private schools can’t use them.
The Social Security tax applies only up to the annual wage base, which is $184,500 in 2026.13Social Security Administration. Contribution and Benefit Base That ceiling is unlikely to matter on substitute wages alone but can come into play if you hold a higher-paying second job. Medicare has no wage cap.
Charter schools are the tricky category. Most operate as private employers under standard FICA rules, but some are organized as arms of a public school district, in which case the district’s Section 218 agreement may govern their employees. If you sub at a charter school and no Social Security deduction shows up on your stub, ask HR whether your position falls under a Section 218 agreement or a FICA replacement plan.
Staffing Agencies and 1099 Classification
Many districts now hire substitutes through third-party staffing agencies. When that happens, the agency is your employer of record and must withhold FICA taxes, regardless of whether the school district itself has a Section 218 exemption.12Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates You’ll get a W-2 from the agency with standard Social Security and Medicare deductions.
Substitutes classified as independent contractors face a different picture. Instead of splitting FICA with an employer, you pay the full 12.4% Social Security tax and 2.9% Medicare tax yourself, a combined 15.3% self-employment tax.14Social Security Administration. Social Security and Medicare Tax Rates You report it on Schedule SE and can deduct the employer-equivalent half from adjusted gross income, but your cash outlay is still meaningfully higher than a W-2 employee’s.
Misclassification happens. The IRS weighs behavioral control (does the school set your hours, assign your classroom, direct your methods?), financial control (does the school supply materials and pay a set daily rate?), and the type of relationship.15Internal Revenue Service. Independent Contractor (Self-Employed) or Employee? Most substitute work looks like employment on all three axes. If a school gives you a 1099 while controlling your day the way an employer would, you may be misclassified, and you can file Form SS-8 with the IRS to request a formal determination of your worker status.16IRS.gov. Instructions for Form SS-8 Determination of Worker Status Note one limit: the IRS won’t issue a determination for state or local government workers whose coverage falls under a Section 218 agreement, and those disputes go to the SSA instead.
How to Check Whether Your Position Is Covered
Start with your pay stub. A line labeled “OASDI” or “Social Security” showing a 6.2% deduction means your position is covered. If you only see the 1.45% Medicare deduction plus a retirement contribution of roughly 7.5%, you’re in a non-covered position with a FICA replacement plan.
For the full record, sign in to your my Social Security account at ssa.gov. Your Social Security Statement lists every year’s covered earnings and your projected retirement benefit.17Social Security Administration. Review Record of Earnings A year with zero or unexpectedly low earnings often means some or all of that year’s wages came from a non-covered position. Errors get harder to correct with time, so it’s worth reviewing early.
For specifics on your district’s Section 218 agreement, contact your state’s Social Security Administrator through the directory at ssa.gov/slge.4Social Security Administration. State Social Security Administrator That office can tell you exactly which positions in your district are covered and which are excluded, information a school payroll office may not have in full.