(3)In the application of sub-section (1) to a case in which an income branch on the property in which the interest in question subsisted has been created by associated operations (as hereinafter defined in section, 25 which included a disposition of that interest, reference to that property shall be construed as reference to that property free from the incumbrance, except in a case in which the incumbrance was created for consideration in money or money's worth which was applied for purposes calculated to maintain or increase the value of the property, and, in that case, shall be construed as reference to that property subject to the incumbrance to the extent to which the consideration was so applied
