See :https://tax.ohio.gov/static/ohiotaxalert/archivedalerts/chanagestounemploymenttax-4621.pdf, which says, in part (at the bottom):
"All other taxpayers who previously filed their federal and Ohio returns prior to the
enactment of this federal deduction and are waiting for the IRS to issue a refund
based on the unemployment benefits deduction do not need to take any additional
action on their originally filed Ohio IT 1040 return (and/or SD 100) at this time.
The Department will provide further guidance when more details are available
from the IRS, please continue to monitor our website.
The IRS’s current guidance on the federal taxation of unemployment benefits can be found here https://www.irs.gov/forms-pubs/new-exclusion-of-up-to-10200-of-unemployment-compensation
and how they will recalculate taxes on unemployment benefits can be found here https://www.irs.gov/newsroom/irs-to-recalculate-taxes-on-unemployment-benefits-refunds-to-start-in-m...
If you have additional questions or need assistance, please visit tax.ohio.gov to email us or call
1-800-282-1780 (1-800-750-0750 for persons who use text telephones (TTYs) or adaptive
telephone equipment), to speak with a taxpayer services representative"
