4.3.4.5. Special Considerations in Partial Acquisitions.In partial acquisitions, the appraiser must make two separate determinations of highest and best use: once for the larger parcel before acquisition, and once for the remainder after acquisition. As J.D. Eaton cautioned: “If the appraiser does not estimate the property’s highest and best use correctly in both the before and after situations, it will be impossible to estimate the property’s value correctly.”415 

The existence and extent of any change in highest and best use due to the government’s acquisition requires careful analysis.416 The highest and best use of the remainder may reflect a complete change, a change in intensity, or no change from the highest and best use of the larger parcel before acquisition.417 A change in a property’s highest and best use may have a positive, negative, or negligible impact on its market value. For example, if what was farmland before acquisition becomes lakefront property with a highest and best use for recreational home sites, offsetting special or direct benefits may apply, as discussed in Section 4.5.5.418 On the other hand, if a remainder property has a less valuable highest and best use after acquisition, the difference in the values before and after acquisition will reflect any compensable diminution in the value of the remainder resulting from acquisition, as discussed in in Section 4.5.2.