The tax rate does not necessarily decline- in your example it is 1.2%. It will still be 1.2%, the total tax bill will decline as prices decline(e.g 1.2%@300k or 1.2%@600k). That is unless the tax rate declines based on the value of the property (e.g 1.2%@300k; 1.6%@600k). Now it would be great if the tax rate also declined!, but I think it is essentially fixed, no?