In the scenario you quoted, the �30,000 is not a profit, it is just the amount you have left from the purchase, so it would not be taxed in any case. The profit is the sale price less the original purchase price(plus the cost of any improvements made). If you have always lived in the house, and have not owned another house which you elected to have treated as your main residence for tax purposes or run a business from the property, then you will not be taxed on any sale profit.