State tax filing

Oh! I did consult a CPA when I started. He reported the cost basis when we started renting based on the house value (I think) from our mortgage statement. Ever since, each year there has been depreciation taken (about ~5k each year) but I don’t think the improvements (40k) were added or depreciated. 

When I try to calculate the costs basis today can I add the improvements (40k) and then deduct the depreciation against that 40k or am I stuck with the $300k (less depreciation ~15k) that’s been reported to the IRS?