Ohio calendar and forms

Ohio runs on the federal calendar. The IT 1040 and the school district SD 100 are due April 15, 2027, the same day as the Form 1040; the four estimated payments fall on the federal dates; and a federal extension carries the Ohio return to October 15, 2027 with no Ohio form to file. The catch is the one every state has: the extension extends the paperwork, not the payment. Ohio charges interest from April 15 on any tax not paid by then, 7% for 2026 and a rate to be announced for 2027, extension or not. The second thing to know is that an Ohio filer may have three returns, not one: the state return, the school district return that is filed with it, and a city return that goes somewhere else entirely.

The form side is more compact than it looks. There is one state return, the IT 1040, and its schedules print as part of it. The SD 100 is a separate return for the roughly 210 school districts that levy an income tax, filed with the state on the same dates through the same system. Every payment of any kind goes in on one coupon, the OUPC. The rest of the list is for part-year residents and people with income taxed in another state.

The 2027 filing season, dated

How the extension works

Ohio has no extension form and no extension of its own. If you have a federal extension, the Ohio IT 1040 and SD 100 are extended to the same date; check the box on the IT 1040 and keep the IRS confirmation number. No federal extension, no Ohio extension. Either way the tax was due April 15. Interest accrues from that date on whatever was not paid, 7% for calendar year 2027, and a late-payment penalty may be added. The way to use the extension without cost is to pay the expected balance by April 15, through OH|TAX eServices as an extension payment or by mail with the OUPC, and file when the return is ready.

Estimated payments

Ohio requires estimated payments when the Ohio tax expected for the year, after credits and withholding, is more than $500. That is half the federal threshold, and it catches people who would never owe estimates federally: a retiree with a $25,000 pension and no Ohio withholding, a part-time landlord, a two-job household where each employer applied the zero bracket. The safe harbor is 90% of this year’s tax or 100% of last year’s, whichever is less, in four equal installments. School district tax has its own estimates on the same dates and the same coupon. The interest penalty for a late or short installment is figured on Form IT/SD 2210. An employer will withhold school district tax once you file a Form IT 4 with the four-digit district number; from 2027 a private pension plan must withhold Ohio tax at a retiree’s request, but for 2026 pension income is still on the retiree to cover.

The forms, in the order a filer meets them

Filing, paying and checking a refund

Most Ohio returns are e-filed with the federal return through software or a preparer. The Department’s own system, OH|TAX eServices at tax.ohio.gov, files the IT 1040, the SD 100 and the IT 10 free, and takes amended returns for the current and three prior years. It also makes every kind of payment, shows up to ten years of transcripts, serves the Form 1099-G for last year’s refund, and runs the refund status check. Payment by electronic check costs nothing; a credit or debit card carries a 2.65% processor fee with a $1 minimum, none of which reaches the state. Payments can be future-dated to the due date.

Direct deposit is available only to e-filers and can go to one checking, savings, IRA or CollegeAdvantage 529 account; the Department says a direct-deposit refund arrives in about 15 business days. A paper return takes eight to ten weeks and gets a check. E-filed returns show up in the refund tracker two to three days after transmission; paper returns take weeks to appear. A return pulled for manual review, often an identity check, is usually refunded within 60 days; the Department asks filers to wait 120 days before calling. Ohio was not part of IRS Direct File.

Paper returns go to the Ohio Department of Taxation at these addresses, with the OUPC enclosed whenever a check is: IT 1040 without payment, PO Box 2679, Columbus OH 43270-2679; IT 1040 with payment, PO Box 2057, Columbus OH 43270-2057; SD 100 without payment, PO Box 182197, Columbus OH 43218-2197; SD 100 with payment, PO Box 182389, Columbus OH 43218-2389. Payments alone for the IT 1040 go to PO Box 182131, Columbus OH 43218-2131.

The individual income tax line is 1-800-282-1780, with TTY at 1-800-750-0750. Registered OH|TAX eServices users can send a secure message instead of calling, which during March and April is the faster route.