That's why both those states are now offering to buy damaged homes from willing sellers at pre-storm values—in order to replace those homes with open land that can serve as buffers for future storms. To determine those pre-storm values, the state is relying on appraisers.

These retrospective appraisals are complex and require great care, but they are extremely important for victims of natural disasters who are looking for a new place to call home. In addition to natural disasters, retrospective appraisals are also used in property tax matters, estate or inheritance tax matters, condemnation proceedings, or suits to recover damages.

To assist with these assignments, the Uniform Standards of Professional Appraisal Practice (USPAP) includes Statement on Appraisal Standards No. 3 (SMT-3) for retrospective appraisals, which can serve as a helpful guide.

Here are four main considerations when conducting a retrospective appraisal:

1. Establish a proper "effective date" right off the bat.
   The first responsibility of an appraiser working on a retrospective appraisal is to communicate with his or her client to establish a proper "effective date." An effective date is the retrospective date on which the appraiser's analyses, opinions, and conclusions are based. This date depends on the purpose and nature of the assignment, so it is critical that an appraiser consult with the client and understand the exact point in time for which the opinion of value applies. In addition to the effective date, an appraiser's report must also include the date on which the report was completed (known as the date of report).

2. Draw upon market data based on that effective date.
   To provide an accurate opinion of value, an appraiser must acquire a thorough understanding of the market at the time of the effective date. The job of the appraiser is to gauge what the property he or she is evaluating would have sold for on the effective date. To do so, an appraiser should utilize market data that was available at the time of the retrospective effective date. In addition, appraisal reports and workfiles from appraisals performed around the time of the effective date may provide valuable information regarding the subject market and comparable properties.

3. Consider more recent market data only if that data reflects a relevant trend.
   Retrospective appraisals are particularly difficult because the appraiser is aware of market data after the effective date. According to USPAP, appraisers are allowed to consider subsequent data if that data reflects a trend which would have been taken into account at the time of the effective date. For example, if an appraiser's analysis of values in the subject property's market area indicated that values were generally increasing, the appraiser could include data subsequent to the effective date of the appraisal to document that particular trend. However, the appraiser is responsible for determining a cutoff date in which he or she will no longer consider subsequent data because information after that point would no longer reflect the market as of the effective date.

4. Communicate using appropriate language.
   While it may seem obvious, it is also crucial that an appraiser use appropriate language and terminology when communicating a retrospective appraisal. The use of the past tense to discuss the conditions of the market at the effective date prevents confusion.

Although retrospective appraisals are very complex and can depend on an appraiser's judgment, they are often vital tools to help people move their lives forward. Complying with USPAP, and SMT-3 in particular, helps to ensure that retrospective appraisals offer an objective analysis of value