CRA indicates that s. 60(o)(i) generates professional fee deductibility from the moment that CRA informs that there is an audit

CRA considers that “subparagraph 60(o)(i) applies to [accord deductibility to] fees or professional fees incurred as part of an audit from the time that the taxpayer was informed that the taxpayer was subject to an audit or new examination respecting the taxpayer’s tax return” as well as to “the professional fees or expenses incurred to mount a challenge before the Administrative Tribunal of Québec following a decision rendered by Retraite Québec concerning the tax credit granting an allowance to families” – but that “professional fees or expenses incurred to make a claim for interest and penalty relief [are] not deductible.”

Neal Armstrong. Summary of 11 October 2019 APFF Roundtable, Q.5 under s. 60(o)(i).