Is my tax based on my equity or my taxable gain?

Tax is calculated upon the taxable gain. Gain and Equity are two separate and distinct items. To determine your gain, identify your original purchase price, deduct any depreciation, which has been previously reported, then add the value of any improvements, which have been made to the property. The resulting figure will reflect your cost or tax basis. Your gain is then calculated by subtracting the cost basis from the net sales price.