Maple Leaf Mills Ltd. v. Minister of National Revenue, 76 DTC 6182, [1976] CTC 324, [1977] 1 S.C.R. 558 -- summary under Timing

The taxpayer, upon its purchase of an oil tanker, received a secured revenue guarantee from the vendors. The amounts of the revenue deficiencies were income to it in the years in which they occurred, notwithstanding that a substantial portion of those amounts would not be payable to it until a sale of the vessel, and notwithstanding that amounts received by it under the agreement would be repayable in the event that revenues from the tanker later exceeded projected levels. "At all material times appellant had a clearly legal right to receive all the benefits that together would bring its income to the guaranteed minimum. There is also no doubt that the right of appellant to the amount of the debt resulting from the deficiency in any given year was held by it unconditionally. That amount was bound to accrue though not necessarily immediately."