My state of domicile is VA but I have worked as a contractor in Ohio for the last 5 years (starting tax year 2011). I travel to Ohio for a week and then go back home. And then go back to Ohio. I do not have an office or a real estate in Ohio. The problem is that for all those years I was filling taxes only in my home state (VA). It turns out that for all these years I should have filled nonresident Ohio taxes but the CPA's that prepared and signed my tax forms never did so. My income is above average and I have substantial tax liability.

What are my steps now?
Obviously I will pay estimated taxes to Ohio for 2016 and file nonresident tax return.

As for the years 2011-2015, do I file nonresident Ohio return and pay tax and possibly penalties and interest and then file VA amended returns and get refund for taxes paid?