Do I have to file a tax return if I don't owe capital gains tax? Capital stock in accounting is ownership value received for preferred and common shares of a corporation.In economics, Capital stock is production assets. By: Irene Bodenstab. Washington state recently passed a capital gains tax as part of an effort to "rebalance" the state's tax system. Capital Stock from PPPs. Washington's capital gains tax rate, including Oregon. Washington's capital gains tax rate, including Oregon. Capital is a financial asset that usually comes with a cost. Here we discuss the four main types of capital: debt, equity, working, and trading.