CRA appears to be prepared to accept that natural gas and oil are similar properties for s. 111(5)(a)(ii) purposes
When commenting on how it has applied the “sale, leasing, rental or development…of similar properties” test in s. 111(5)(a)(ii), CRA noted that it still considers the “similar properties” term to reference a narrower meaning than “having characteristics in common” and that it instead references properties “of the same general nature or character.”
In discussing how it has applied this test, CRA noted that 9234795 stated that oil or gas from wells located in different provinces would be considered to be a “similar property,” and that although CRA has not taken a position on whether the different types of hydrocarbons are similar to each other, in 9314945 it “opined that where a corporation carries on the business of mining and selling metallurgical coal as well as the business of mining and selling other minerals, income therefrom will be considered to be derived by those businesses from the “sale, leasing, rental or development…of similar properties” for the purposes of subparagraph 111(5)(a)(ii) provided that the other conditions in paragraph (a) are met.” This appears to suggest that natural gas and oil would be accepted as similar properties.
Neal Armstrong. Summary of 7 June 2017 Canadian Petroleum Tax Society Roundtable, Q.4 under s. 111(5)(a)(ii).