report to management

There is no specific date. If you look at Chapter 6/7 overview of an audit – you will see that the auditor may report deficiencies during the audit (because controls were expected to be effective but tests of controls show that they are not operating effectively) or at the end of the audit.

Unlike the representation letter, the weakness letter is not audit evidence. The representation letter has to be obtained before the auditor’s report is signed. The weakness letter is more a “by-product” of the audit (don’t say this to the examiner – it’s just a way of thinking of it). So it could be sent after the date of the auditor’s report. Timing will depend on how significant the weaknesses are and how urgently the matter should be addressed by TCWG/management.