A friend explained this to me in detail. The "retrospective value" is the "as is" value. He prefers to remain anonymous but said that I could share this.
All banks require an as-is appraisal when originating a loan that must be consistent with the Interagency Appraisal & Evaluation Guidelines (IAEG); the IAEG outlines what is necessary to comply with FIRREA with regard to appraisals.
As you know, an as-is appraisal can be made with EAs. An as-is appraisal cannot be made with any HCs. Simple so far (no news to you).
As-is isn’t dependent on the date; it is dependent on the condition of the property as of the date of value.
Here is the definition of from the IAEG (my bold for emphasis):
‘‘As Is’’ Market Value—The estimate of the market value of real property in its current physical condition, use, and zoning as of the appraisal’s effective date.
The effective date is always the benchmark date for the valuation; an opinion of market value of a property 10-years ago with no hypothetical conditions would be the as-is value of that property as of that date.
The terms “retrospective” and “prospective” provide a reference date of the appraisal development and reporting. The property’s as-is condition as of the development/reporting date is not the benchmark date for its condition, etc., as of the effective date.
An as-is opinion of market value can be developed in either case because “as is” doesn’t reflect the condition the property is in as of the date of report development and communication, it represents the condition of the property as-of the effective date.
A bank could have many valid reasons for asking for a retrospective value; they certainly have many valid reasons for asking for a prospective value (as-complete and as-stabilized). This is also covered in the IAEG:
Effective Date of the Appraisal— USPAP requires that each appraisal report specifies the effective date of the appraisal and the date of the report. The date of the report indicates the perspective from which the appraiser is examining the market. The effective date of the appraisal establishes the context for the value opinion. Three categories of effective dates— retrospective, current, or prospective— may be used, according to the intended use of the appraisal assignment.