To file Ohio Form SD 100, confirm that your school district levies an income tax, look up your four-digit district number and tax base, calculate what you owe using either the traditional or earned income method, and submit the return with your Ohio IT 1040 by April 15. You can file electronically through OH|TAX eServices or mail a paper return to the Ohio Department of Taxation. About 214 Ohio school districts impose this tax at rates between 0.25% and 2.00%, so the first job is figuring out whether yours is one of them.1Ohio Department of Taxation. School District Tax Year 2026
Confirm You Actually Owe School District Tax
You owe school district income tax if you lived in a taxing district at any point during the year, had income while you lived there, and show a tax liability on line 8 of the SD 100. Residency is what triggers the tax. Under Ohio law, you are a resident of a school district if you are domiciled there or maintain a permanent place of abode there for all or part of the year.2Ohio Legislative Service Commission. Ohio Code 5748.01 – School District Income Tax Definitions Full-year residents report all income earned during the calendar year. Part-year residents calculate tax only for the portion of the year they lived in the district.
One point catches many filers off guard: you can owe school district tax even when your Ohio IT 1040 shows zero liability, so you may need to file both returns regardless.3Ohio Department of Taxation. School District Income Tax
Working in a taxing district is not the same as living in one. If you work in a taxing district but live outside it, you generally do not owe the tax. Check your W-2 to make sure an employer is not withholding school district tax by mistake.
If you are an active-duty servicemember with Ohio as your legal residence but you are stationed outside the state, your military pay is not subject to Ohio or school district income tax. If you are stationed in Ohio and live in a taxing district, your military pay is taxable. Non-military income earned as an Ohio resident, such as rental income or a civilian side job, can still create a filing requirement, and the Department recommends filing an SD 100 even if you believe you owe nothing.4Ohio Department of Taxation. Military Servicemembers and Ohio Income Taxes
Find Your District Number
Every taxing school district has a four-digit identification number that goes at the top of your SD 100. Getting it wrong can cause processing delays or a delinquency notice. The fastest way to find it is the state’s online lookup tool, called The Finder. Type in your home address and you get back your district name, number, and current tax rate.5Ohio Department of Taxation. The Finder – School District Income Tax
Your number also appears on the Department’s published list of school districts, which is updated each tax year.6Ohio Department of Taxation. 2025 Ohio School Districts If your employer has already been withholding school district tax, the district number should be printed in the local tax section of your W-2.
Know Which Tax Base Your District Uses
Each taxing district uses one of two tax bases, and the SD 100 is calculated differently for each. The Finder tells you which base applies alongside the rate. Using the wrong one is among the most common errors on this return.
Traditional Tax Base
The traditional base starts with your Ohio modified adjusted gross income, which carries over from your IT 1040. This is the broader of the two bases: it includes wages, interest, dividends, capital gains, retirement distributions, and other income. You subtract your personal exemptions to arrive at taxable school district income, then multiply by your district’s rate.2Ohio Legislative Service Commission. Ohio Code 5748.01 – School District Income Tax Definitions The exemption amount depends on your modified AGI and phases out at $500,000.7Ohio Legislative Service Commission. Ohio Revised Code 5747.025 – Personal Exemptions
Earned Income Tax Base
The earned income base is narrower. It taxes only wages, salaries, tips, other employee compensation, and net earnings from self-employment. Interest, dividends, capital gains, and most retirement income are excluded, which often works out well for retirees and investors who live in these districts. Add up only those earned amounts, then multiply by the district’s rate.
Fill Out the Form
Have your completed federal return, your Ohio IT 1040, and any W-2s showing school district tax withheld in front of you before starting. The SD 100 is short, but each section builds on the one before it.
Header and Residency Dates
Enter your name, Social Security number, and the four-digit school district number at the top. If you moved during the year, you may need to file a separate SD 100 for each taxing district you lived in, with the exact residency dates for each so the tax applies only to the income earned during each period.
Calculate the Tax
For a traditional-base district, bring over your Ohio modified adjusted gross income from the IT 1040, subtract your personal exemptions, and multiply the result by your district’s rate. For an earned-income district, total your wages and net self-employment income, leaving out investment and retirement income, and multiply by the rate.
If you were 65 or older by the end of the tax year, you can claim a $50 senior citizen credit, which comes straight off the tax owed.
Apply Withholding and Payments
After calculating the tax, enter any school district tax your employer withheld during the year. The amount appears in the local tax section of your W-2, and the district number listed there should match the one on your return. Add any estimated payments you made during the year. If your withholding and payments add up to more than your liability, you can take a refund or apply the overpayment to next year. If they fall short, you owe the difference.
Submit the Return
You can file the SD 100 electronically or on paper. Electronic filing is faster, reduces errors, and processes refunds sooner.
Electronic Filing
Ohio’s free OH|TAX eServices system walks you through each line and runs the calculations for you. You can also e-file through commercial tax software or have an authorized tax preparer transmit the return.8Ohio Department of Taxation. OH|TAX eServices – File Now
Paper Filing
If you mail the return, the address depends on whether you are enclosing a payment:
- No payment: Ohio Department of Taxation, P.O. Box 182197, Columbus, OH 43218-2197
- With payment: Ohio Department of Taxation, P.O. Box 182389, Columbus, OH 43218-2389
Sending the return to the wrong P.O. Box can delay processing and trigger late-payment interest.9Ohio Department of Taxation. Mailing Addresses
When mailing a payment, include the Ohio Universal Payment Coupon (OUPC), which has replaced the older SD 40P voucher and now covers all individual and school district tax payments. Make your check or money order payable to “School District Income Tax” and write the tax year, the last four digits of your Social Security number, and your school district number on the memo line.10Ohio Department of Taxation. Tax Forms
Deadline and Extensions
The SD 100 is due April 15, the same date as the IT 1040. If you file for a federal extension on IRS Form 4868, Ohio automatically extends your SD 100 deadline to October 15. When you file the return, check the box indicating you filed Form 4868 and include a copy of the federal extension.11Ohio Department of Taxation. Ohio’s Individual and School District Income Tax Filing Extension Deadline
An extension gives you more time to file, not more time to pay. Interest accrues on any unpaid tax starting April 15, even with a valid extension in place.
If you expect your school district tax liability minus withholding to exceed $500, you should also make quarterly estimated payments during the year to avoid an underpayment penalty. This commonly applies to the self-employed, retirees with no withholding, and anyone with significant income outside employer withholding.12Ohio Department of Taxation. Estimated Payments
Penalties and Interest for Late or Underpaid Returns
The Ohio Tax Commissioner certifies a new interest rate each October, based on the federal short-term rate plus three percentage points. For calendar year 2026, the interest rate on overdue school district taxes is 7%.13Ohio Department of Taxation. Annual Certified Interest Rates
If you did not pay enough through withholding or estimated payments during the year, the Department applies a 2210 interest penalty on line 9 of the SD 100. This penalty is required by law and generally cannot be removed, though the Department may adjust it if payments were miscalculated or not properly credited.14Ohio Department of Taxation. Individual and School District Income Tax – 2210 Interest Penalty
A separate failure-to-file penalty applies if you miss the due date entirely. It is the greater of $50 per month (up to $500) or 5% of the unpaid tax per month (up to 50% of the tax owed).
Fixing a Mistake After You File
If you spot an error on a return you already submitted, correct it by filing an amended SD 100. Ohio consolidated the original and amended school district returns into a single form starting with tax year 2015, so you use the same SD 100 and check the amended box.15Ohio Department of Taxation. Ohio Amended School District Income Tax Return For faster processing, file the amended return through OH|TAX eServices for any tax year still within the statute of limitations. Paper amended returns can take several months to work through.