Thousands of Ohio businesses are due a tax refund.

Ohio government is starting to return nearly $14 million to 3,500 Ohio businesses who “unknowingly overpaid” their commercial activity tax, Gov. John Kasich’s office said Tuesday.

Kasich’s office said the state now will notify a business when it has overpaid and help them with the process of claiming a refund, Kasich’s office said in a statement.

Previously, the state did not notify businesses of overpayments even if it was aware of them, the governor’s office said. Businesses were expected to uncover the overpayment themselves, and then only “within a certain amount of time” if they wanted to get a refund, according to the governor’s office.

Gary Gudmundson, an Ohio Department of Taxation spokesman, said he couldn’t answer questions about how many area businesses are eligible for refunds due to confidentiality restraints. But the department is reviewing the CAT tax records of more than 184,000 taxpayers, according to a “fact sheet” that accompanied Kasich’s announcement. About 11,000 businesses could “ultimately be found to be eligible for a tax refund,” the fact sheet said.

The state will notify businesses eligible for refunds, Gudmundson said. “We have thousands of accounts to evaluate and as we make findings on potential eligibility, we will send them (businesses) letters notifying them of their status,” he said in an email.

Consolidated Millwork Supply, a distributor of doors, frames and hardware in Dayton, agreed to help the state publicize the new policy. The company got a refund of $20,332.52.

Company owner Mike Vagedes said his treasurer was in Columbus Tuesday to get a refund check. He has six employees and has operated since 1979. The refund is due to an accounting “mistake” made in 2008, and while the refund is welcome, he finds himself wondering if his business has made other similar errors, he said.

“If nobody had mentioned anything, I wouldn’t know any different,” Vagedes said.

In 2005, Ohio legislators approved a commercial activity tax, replacing the franchise tax and tangible personal property tax. That tax impacts all businesses based on a portion of gross receipts, not net income.

Refund request forms and more information are available at www.tax.ohio.gov.