Taxation Conformity Updates

Conformity Updates 

[Update as of 10/16/2018]

Ohio law requires the General Assembly to pass legislation, when federal law is changed, to adopt, or conform to, those changes for Ohio tax purposes. As of March 30, 2018, Ohio is in conformity for tax years 2017 and prior. For the most recent conformity announcement, see the following link:

Applies to taxable year 2017 (PDF)

Ohio's conformity statute is found in R.C. 5701.11. Division (A) of R.C. 5701.11 states that any reference in the tax chapters of the Ohio Revised Code to the "Internal Revenue Code" means the Internal Revenue Code (IRC) as it exists on the effective date of the statute (currently March 30, 2018).

Division (B)(1) of R.C. 5701.11 allows a taxpayer to irrevocably elect either 1) the version of the Internal Revenue Code adopted by Ohio as of the end of the taxpayer's taxable year or 2) the version of the Internal Revenue Code as it existed after Ohio conformity under R.C. 5701.11(A). This election exists to allow taxpayers to take advantage of relevant tax deductions/ credits that become part of Ohio law after the close of the taxpayer's tax year, while also avoiding retroactive tax increases.

Please note: A person must elect one version of the Internal Revenue Code or the other; the person cannot selectively incorporate some provisions from each version of the IRC.  The Department will presume an election to conform with the most current version of the IRC (as of the March 30, 2018 effective date), and thus no statement is necessary or required to elect conformity. 

To elect the prior version of the IRC, a person should submit the two required items together to the Department before filing their affected return:

1. The following statement:

“Pursuant to R.C. 5701.11(B)(1), [person’s name] hereby irrevocably elects to use the version of the Internal Revenue Code as it existed on [effective date].”

When completing this statement, the “person’s name” is the individual or entity’s name and the “effective date” is the previous effective date for R.C. 5701.11.  For example, if the taxpayer did not wish to conform for tax year 2017, it would select “March 30, 2017” as the effective date.

In addition to including the statement previously described, please list your full name, entity name and FEIN (if applicable), last four digits of your SSN (if applicable), current mailing address, and contact phone number.

2. Any supporting documentation and/or statements to further validate a deduction or credit being claimed on the forthcoming affected return.

Any person that intended to elect the Internal Revenue Code as it existed on March 30, 2017, should submit the above statement and supporting documentation prior to filing the affected return to:

Ohio Department of Taxation
Personal & School District Income Tax Division
P.O. Box 182847
Columbus, OH 43218-2847
Fax: (253) 234-1369

Please note: This guidance does not apply to those who have already filed their return on or before October 16, 2018.

To see this message on our website, or to obtain information on Ohio conformity for other taxable years, please go to

Questions. If you have additional questions or require more information, please visit, click on the “Contact” link found at the top right of the page and then choose the “Email Us” option. Taxpayers with additional questions regarding this subject can also contact Individual Income Taxpayer Services at 1-800-282-1780, or at 1-800-750-0750 for the hearing impaired.