Appraisal assumption treated as true for the analysis even though it could affect value if wrong.
An extraordinary assumption is an appraisal assumption treated as true for the analysis even though it could affect value if the assumption is wrong.
Extraordinary assumption matters because it flags uncertainty inside the valuation. The appraisal may be usable only if the stated assumption turns out to be true.
For mortgage borrowers, the term matters when the report depends on information that has not been fully verified, a condition that may change, or a fact that could materially affect collateral value. It is a disclosure of uncertainty, not permission to use an arbitrary guess.
Borrowers encounter extraordinary-assumption language in the Appraisal Report, often in the assignment conditions, comments, or limiting conditions.
The term becomes practical when underwriting or appraisal review asks whether the assumption needs support before the loan can close. The lender may accept the report as written, request documentation, obtain a correction, or require additional valuation work depending on the importance of the assumed fact.
| Report language | Borrower-facing meaning |
|---|---|
| Assumption is stated | The appraiser is relying on a condition as true |
| Assumption could affect value | The value might change if the assumption is wrong |
| Lender review may follow | The file may need documentation or clarification |
An extraordinary assumption generally addresses a fact that could be true but is uncertain on the effective date. Examples can include relying on a represented characteristic that was not observable under the assignment’s inspection scope or assuming a reported legal or physical fact is accurate while verification remains incomplete.
The report should identify the assumption and make clear that using it could affect the assignment result. If the fact is later shown to be false, the original opinion may need to be reconsidered rather than silently treated as unchanged.
An appraiser cannot access a detached structure during the required property observation. Reliable records describe its permitted use and physical characteristics, and the report treats that information as true through an extraordinary assumption.
If later evidence shows that the structure is materially different or not legally usable as represented, the appraisal conclusion may require review. The assumption did not guarantee the fact; it disclosed how the appraiser handled the uncertainty.
Ask four questions when the phrase appears:
That last question is the practical one. Some uncertain facts have little impact, while others affect marketability, legal use, condition, or the comparable analysis enough to alter the value opinion.
| Follow-up | What it can accomplish |
|---|---|
| Existing document | Supports the assumed legal or physical fact |
| Clarification from appraiser | Explains the assumption’s role in the analysis |
| Additional inspection or evidence | Resolves an observation gap |
| Appraisal review | Determines whether the report is acceptable for lender use |
| Revised or new appraisal work | Addresses a material false assumption |
An extraordinary assumption is not automatically a defect. It becomes a problem when it is unreasonable, poorly disclosed, or material evidence later contradicts it.
Extraordinary assumption differs from Hypothetical Condition because an extraordinary assumption is treated as true but uncertain, while a hypothetical condition is knowingly contrary to current fact or not yet true for the analysis.
It differs from Subject-To Appraisal because subject-to appraisal describes a value conditioned on completion or correction of specified items.
It also differs from Appraisal Review because review is the lender-side check that may evaluate whether the assumption is acceptable.
It differs from a routine assumption because the extraordinary assumption concerns uncertainty significant enough that being wrong could affect the assignment result.