813. Consideration due after the time of disposal.

In the computation of a gain resulting from the disposal of an asset, consideration for the disposal must be brought into account without any discount for postponement of the right to receive any part of it and, in the first instance, without regard to a risk of any part of the consideration being irrecoverable or to the right to receive any part of it being contingent1. If any part of the consideration so brought into account subsequently proves to be irrecoverable, such consequential adjustment as may be required must be made by way of discharge or repayment of tax