1.2.7.3.4. Before and After Rule. In partial acquisitions, these Standards require application of the before and after rule, also known as the federal rule, in which the appraiser estimates both the market value of the larger parcel before the government’s acquisition and the market value of the remainder property after the government’s acquisition.32 Requiring this method of valuation allows acquiring agencies, the Department of Justice, and the courts to calculate a reasonable measure of compensation by deducting the appraiser’s estimated remainder or after value from the appraiser’s estimate of the larger parcel’s before value. The result of this procedure is a figure that includes the value of the property acquired as well as any compensable damages and/or special benefits to the remainder property. 

Appraisers should note that these are two separate appraisals within the same assignment and require the appraiser to perform a new analysis and valuation of the remainder after the acquisition.