I recently appraised a newer Colonial style dwelling located in a recently developed sub-division.  I typically do pre-inspection research on the subject property and surrounding area before the interior observation before every appraisal that I complete.  In this instance, it was noted that the Town Assessor and Listing Agent reported the Colonial to be a 2,100 square foot dwelling.  Later that day, I went out to the subject property and measured the exterior with my laser measurer and confirmed the 2,100 square feet.  However, the interior observation revealed a 450 square foot "Bonus Room" that was not noted by the Assessor or the Listing Agent.  I noted in the appraisal that the appraiser measured the property and the differential in GLA as reported in the report was 450 square feet larger than the GLA as reported by the Assessor - due to this finished Bonus Room (in this instance a permit had been obtained - however, the Assessor had never updated their records - this is more common that you may think!).  Two days before closing the Underwriter contacted me with the following revision request, " Thank you for the detailed report.  Please confirm that the Bonus Room exists as the Assessor does NOT report this and the MLS listing photos do not have a photo of this room.  Please also include an explanation of how this area was measured - Thanks!"