When formulating the relevant key considerations in determining what additional audit evidence to obtain about controls operating during the roll-forward period are, the auditor must follow paragraph 56 of the Audit Standard AS 2201.
Paragraph 56 states that there are four factors that determine what additional evidence is needed. First, the auditor should consider “the specific control tested prior to the as-of date, including the risks associated with the control and the nature of the control, and the results of those tests”. Then, “the sufficiency of the evidence of effectiveness obtained at an interim date” and “the length of the remaining period” should be analyzed.
The final factor is the possibility of “any significant changes in internal control over financial reporting subsequent to the interim date”. In essence, the more uncertainty in the effectiveness of the controls there is, the more additional evidence is required.