CRA is prepared to infer a refund request from a waiver

In clarifying 2012-0468081I7, CRA has stated that although a waiver itself does not extend the deadline for a taxpayer to apply under s. 164(1)(b) for an income tax refund, it will treat the waiver as such an application where "it is reasonable to conclude the waiver also contains an implicit request for a refund for the particular issue outlined in the waiver."  Of course, it is preferable for the waiver to be explicit on this point.

Neal Armstrong.  Summary of 15 June 2015 Memo 2015-0583081I7 under s. 164(1).