SAS 72

“Statement on Auditing Standards No. 72, Letters for Underwriters and Certain Other Requesting Parties” promulgated by the US Auditing Standards Board. Provides the criteria and guidelines for a Comfort Letter. The 135-Day Rule is derived from AU Section 634, generally referred to as SAS 72/AS 6101, which notes that auditors will generally provide comfort (including Negative Assurance on Financial Statement(s) that are less than 135 days old.