Record retention requirement mandates extended preservation of GST accounts and related records, with longer retention during appeals or investigations. Registered persons must retain books of account and other records for a statutory period measured from the due date for furnishing the annual return to which those records relate; if the person is party to appeal, revision, other proceedings, or under investigation for an offence, records relevant to that matter must be retained for the longer of the post-disposal retention interval or the base statutory period.