 In adopting the Receipts and Expenditure Method or the Contractor's Method, the important final valuation step for the valuer must always be to stand back and examine the outcome to ensure it is reasonable as a value for the tenement as it stands, having considered the viewpoints of both the hypothetical landlord and the hypothetical tenant.Rental levels for different types of property and for properties in different locations may change over time by varying amounts due to many factors, including economic, social and demographic changes which affect property values.It is important that the rateable values, on which rates are charged, are updated regularly to reflect changes in market rental values in order to provide a sound and equitable tax base.