For instalment sales of immovable property under s.10 of the Capital Gains Tax Act — apportion the total gain over the years in which instalments are received.
Total gain = Sale − Selling exp. − (Cost + Improvements + Inflation)
Gain ratio = Total gain ÷ Total sale price
This year = Instalment received × Gain ratio
CGT this year = This year's gain × 20%
Until cumulative instalments equal the sale price.