Fannie Mae stipulated changes to several calculations in the Market Conditions Addendum to the Appraisal Report (Form 1004MC), requiring appraisers to use the new calculations for all mortgage loan applications dated on and after September 1, 2010. Refer to page 4 in the document linked below for the updated guidelines from Fannie Mae:
Fannie Mae Market Conditions 1004MC Resources
You will need Adobe Acrobat and Microsoft Excel or a Microsoft Office Compatible Program to use these documents. If you don’t have Microsoft Office, they should work with Adobe Acrobat and http://www.openoffice.org, a free open source alternative.
Fannie Mae Market Conditions 1004MC Instructions Opens in Adobe Acrobat
Fannie Mae Market Conditions 1004MC Spreadsheet, Rev. 9/1/16 Opens in Microsoft Excel