For purposes of the right of rescission (12 C.F.R. 1026.23) the definition rules in Regulation Z (12 C.F.R. 1026.35) states that you use the “specific day” definition of business day. Under the specific day definition a business day is all calendar days except for Sunday and federal holidays. Saturday is a business day whether your lobby is open or not.
Requirements for delivering a copy of the appraisal are contained in both Regulations B (12 CFR 1002.14) and Z(1026.35). Regulation B uses the term “business day,”but does not define the term. For purposes of delivering a copy of the appraisal, as required by Regulation Z (12 C.F.R. 1026.35) the term business day uses the “general rule” which defines a business day as any for which your financial institution is open for substantially all of its business functions. There is a wee bit of a judgment call in what constitutes “substantially all” business functions. If your customers can obtain substantially all business functions in any office on a Saturday, then Saturday is deemed to be a business day for purposes of delivering a copy of an appraisal, otherwise it is not.