Provigo Inc. v. Canada, 2009 DTC 5877, 2008 FCA 205 -- summary under Paragraph 20(1)(f)

The taxpayer, which pursuant to a right accorded to it in debentures, repaid the debentures by issuing shares with a fair market value greater than the principal, was not permitted to deduct the excess value of the shares under s. 20(1)(f). The deduction under s. 20(1)(f) "is limited to a 'point-in-time expense' represented by the discount calculated at the time an obligation was issued, so that no deduction was available for an alleged appreciation of the principal amount over time". (para 8).