If an appraiser cannot use sales comparison or income capitalization, which approach must they apply?

The cost approach is indeed the appropriate method to employ when an appraiser is unable to use the sales comparison or income capitalization approaches. This situation may arise in specific scenarios, such as when there are no comparable sales data available or when the property being appraised does not generate income, making it impossible to utilize the income approach.

The cost approach involves estimating the cost to replace or reproduce the subject property, then adjusting for depreciation, which accounts for wear and tear, functional obsolescence, and economic obsolescence. This method is particularly useful for properties that are unique, new, or not frequently bought or sold in the market. By utilizing this approach, the appraiser can derive a value based on the cost of constructing a similar asset, which might provide a viable estimate in the absence of traditional comparative or income data.

In contrast, the other approaches mentioned—market, income, and sales—are either alternative names for the sales comparison approach or methods that rely on data that is not available in this context. Thus, the cost approach stands out as the sole remaining option in scenarios where the other methods cannot be effectively applied.