Randy Carey
The use of a Fannie Mae 1003 application would be a requirement imposed by the bank itself or an investor to which you are selling the loan. There is no regulatory requirement to ever use this form.
Jim Bedsole
The only requirements to use a specific form 1003 application are secondary market requirements either from an investor (as in a correspondent relationship) or agency (such as Fannie Mae, Freddie Mac, HUD, or VA) requirement. Those requirements will apply to any secondary market loan transaction covered by that investor or agency. For a portfolio loan, there is no regulatory requirement that I'm aware of to use a Form 1003 application for any transaction. There is only a requirement in Reg B that a written application form must be used for loans covered by Section 1002.13 -- but does not specify any particular format for that application form.
Andy Zavoina
While not a requirement, the 1003 is the perfect application to capture the data required for the underwriting of the loan. The OCC's Fair Housing Home Loan Data System (if this applies to you) requires that you attempt to collect various data elements. If you used other than the 1003 or a suitable substitute, you may miss some of the required data. By using the correct form, you have attempted collection, even if the applicant skipped it.