A $1 error in the amounts used in a suppression election can invalidate the election

Where the winding-up under s. 88(3) of a foreign subsidiary of Canco would otherwise result in a capital gain to Canco (e.g., because of high inside basis of the distributed assets and insufficient exempt surplus), Canco can make a suppression election under s. 88(3.3) to in effect reduce the high basis of the distributed assets and, thus, the proceeds of disposition of its shares of the subsidiary.  However, the amount of this reduction cannot exceed what otherwise would be the capital gain on Canco’s disposition of its shares of the subsidiary – otherwise the election is completely invalidated.

Accordingly, if Canco makes the suppression election on the basis of estimated proceeds of disposition of its shares of the subsidiary (based on the inside basis) that later turns out to have been too high or on the basis of an estimated adjusted cost base of its shares of the subsidiary that is too low, the election will be invalidated.

Neal Armstrong.  Summary of Clara Pham and Alex Feness, "CFA Suppression Election: Potential Risks", Canadian Tax Focus, Vol. 3, No. 3, August 2013, p. 2 under s. 88(3.4).