Accountants providing opinions on corporate financial statements are required to consider whether the corporation has made adequate provision in its accounts for possible tax reassessments. The accountant is required to consider and analyze various claims, deductions or business or tax strategies which have resulted in tax reductions from what might otherwise have been paid in order to perform this analysis, and the accountant must retain documentation regarding this review.  In June 2010 the CRA released a policy paper outlining its views and position regarding the CRA's access to accountants' files, including the review of the adequacy of a corporation's tax liability provision. Not surprisingy, the CRA took the position that it had a virtually unfettered right to request and review such files, includingtax accrual working papers (including those that relate to reserves for current, future, potential or contingent tax liabilities.   

The Federal Court has now had a chance to review this issue and has unfortunately sided with the CRA. The Federal Court in Canada v BP Canada Energy Company, 2015 FC714 held that the CRA was entitled to tax accrual working papers of the external accountants and held that there was no compelling reason of public policy to deny the Minister's access to such documents. At the time of writing it is unknown whether BP has or will appeal this ruling.