Does one have to pay state tax on foreign capital gain and foreign interest that was earned during that year?

Yes. Like the IRS, Ohio takes the world-wide income of all of its residents.

Ohio taxes capital gains (foreign or domestic) and interest (foreign or domestic) as ordinary income.

Now, if you are a non-resident, then only income earned while working IN Ohio is subject to Ohio income tax.

@AtlantaExpert, at what rate?

Ohio's income tax has nine tax brackets that range from 0.587% to 5.95%, depending on your income level. The top bracket kicks in at $200K income. Several municipalities also levy their own income tax, so depending where you live you may have to pay that as well.

Thanks, ebaines!