To fill out Ohio Form SD 100, finish your Ohio IT 1040 first, look up your four-digit school district number and tax type on The Finder, then complete either the traditional tax base lines (19–23) or the earned income base lines (24–27) for each district you lived in during the year. Apply any withholding shown on your W-2 and the $50 senior credit if you qualify, and file by April 15, 2026 for tax year 2025.1Ohio Department of Taxation. Due Dates Since 2023, Ohio uses a single consolidated SD 100 that handles every district you lived in on one return.2Ohio Department of Taxation. School District Income Tax
What to Have in Front of You
The SD 100 pulls numbers directly from your state return, so your completed Ohio IT 1040 needs to come first. Beyond that, gather:
- All W-2s, paying attention to boxes 14, 19, and 20, where school district withholding appears with a four-digit district code
- Any 1099s showing retirement, interest, dividend, or self-employment income
- Your four-digit school district number (not your zip code) and your district’s tax type
You only need to file an SD 100 if you lived in a taxing school district at some point during the year, had income while living there, and the calculation on line 8 produces a liability.2Ohio Department of Taxation. School District Income Tax If your district’s rate is 0%, there is no tax and no return. About 224 districts statewide impose the tax, at rates from 0.25% up to 2%.3Ohio Department of Taxation. Taxing School Districts Effective January 1, 2025
Look Up Your District Number and Tax Type First
Every taxing school district has a unique four-digit number, and the SD 100 cannot be completed correctly without it. The Ohio Department of Taxation runs a free lookup called The Finder. Enter your street address, city, and zip code, and it returns your district number, the tax rate, and the tax type.4Ohio Department of Taxation. The Finder – School District Income Tax – Lookup By Address You can also enter a specific date, which matters if you moved during the year and need information for each prior address.
The tax type is the critical piece: it tells you whether your district uses the traditional tax base or the earned income tax base. That choice decides which section of the form you fill out and which income gets taxed. If you lived in a non-taxing district for part of the year, enter 9999 as the district number for that period.5Ohio Department of Taxation. 2025 SD 100 – School District Income Tax Return
Traditional Base or Earned Income Base
Ohio Revised Code 5748.01 defines the two bases a district can adopt.6Ohio Legislative Service Commission. Ohio Revised Code 5748.01 – School District Income Tax Definitions You complete only the section matching your district’s choice.
The traditional tax base starts with your Ohio modified adjusted gross income and includes wages, investment income, retirement distributions, rental income, and most other sources reported on your IT 1040, minus exemptions under section 5747.025. This is the broader base and produces a higher taxable figure for anyone with significant non-wage income.
The earned income tax base taxes only wages, salaries, tips, other employee compensation, and net self-employment earnings, each to the extent included in your modified adjusted gross income. Retirement income, dividends, capital gains, interest, and rental income are excluded. A retiree in an earned income district whose only income is a pension and Social Security often owes nothing.
Filling Out the Form
Header and Filing Status
Enter your name, Social Security number, and current address at the top. Your filing status must match the one on your Ohio IT 1040. If you obtained a federal filing extension, check the box on page one indicating that.5Ohio Department of Taxation. 2025 SD 100 – School District Income Tax Return The consolidated return then asks you to complete a schedule for each school district you (and your spouse, if filing jointly) lived in during the year.
Lines 19–23: Traditional Base Districts
Line 19 pulls your Ohio adjusted gross income from line 3 of your IT 1040. Ohio then allows adjustments depending on the district’s levy, such as subtracting interest from federal government obligations and certain retirement income. Part-year residents use line 22 to subtract income earned while living outside the district. Full-year nonresidents enter the entire line 21 amount on line 22. The result on line 23 carries to line 1 of the return.5Ohio Department of Taxation. 2025 SD 100 – School District Income Tax Return
Lines 24–27: Earned Income Base Districts
Line 24 is for wages, salaries, and tips you received while living in the district and that are included in your modified adjusted gross income. Line 25 captures net self-employment earnings under the same residency and inclusion conditions. Line 26 is for federal conformity adjustments only; do not enter federal Schedule A deductions here. The total on line 27 carries to line 1.
Tax, Senior Credit, and Withholding
Multiply the taxable income on line 1 by your district’s rate to get the tax. Taxpayers 65 or older can take a $50 senior citizen credit directly on the SD 100, reducing the tax dollar for dollar.7Ohio Department of Taxation. Senior Citizens and Ohio Income Tax School district withholding from your W-2, generally in box 19 or 20 with a four-digit district code, is credited against the tax.2Ohio Department of Taxation. School District Income Tax Under the consolidated form, withholding from any district is pooled and applied to any balance due for the year.
One note on payments: if your expected liability minus withholding and credits is more than $500, you should be making quarterly estimated payments on form SD 100ES during the year rather than catching up on the SD 100.8Ohio Department of Taxation. SD 100ES – Estimated Payment Missing those triggers an underpayment interest penalty calculated on Form IT/SD 2210.
Filing and Paying
You can file electronically through OH|Tax eServices at myportal.tax.ohio.gov, free of charge, and most commercial tax software supports the SD 100 alongside the IT 1040.2Ohio Department of Taxation. School District Income Tax Electronic filing gives you immediate confirmation and faster refund processing.
If you file on paper, the mailing address depends on whether you owe:5Ohio Department of Taxation. 2025 SD 100 – School District Income Tax Return
- No payment included: Ohio Department of Taxation, P.O. Box 182197, Columbus, OH 43218-2197
- Payment included: Ohio Department of Taxation, P.O. Box 182389, Columbus, OH 43218-2389
Make checks or money orders payable to Ohio Treasurer of State. You can also pay online through OH|Tax eServices and mail just the return to the no-payment address.
Deadline, Extensions, and Late Penalties
The SD 100 for tax year 2025 is due April 15, 2026, the same day as your federal and Ohio returns.1Ohio Department of Taxation. Due Dates A federal extension automatically extends your SD 100 filing deadline to October 15, 2026, with no separate Ohio extension form required.
An extension only extends time to file, not time to pay. Any tax owed is still due April 15, and interest accrues on unpaid balances from that date at a rate set annually by the state tax commissioner. The late-filing penalty can reach $50 per month up to a $500 maximum. Filing on time even when you cannot pay in full avoids the filing penalty and leaves only interest on the unpaid amount.