Although, as a general rule the inclusion/deduction mechanism provided under ss.12(1)(a), 12(1)(e) and 20(1)(m) should apply to amounts received in a year by a taxpayer in the course of a business in respect of services not rendered or goods not delivered before the end of the year or that otherwise may be regarded as not having been earned in the year, in some circumstances a full inclusion (without reserve) under s. 9(1) may be more appropriate, for example, where the taxpayer has substantially performed all its obligations, or where the taxpayer would be allowed to retain the prepayment even if it did not perform.