Words and Phrases - "tax otherwise payable under this Part"

Did the (former) corporate surtax under s. 123.2 form part of the tax otherwise payable under Part I respecting the federal logging tax credit under s. 127(1)? After referring to the s. 117(1) definition of "tax otherwise payable under this Part," CRA stated:

The rules for calculating the tax applicable to corporations (including the corporate surtax) and those applicable to all taxpayers (including the federal tax credit for forestry operations) are found respectively in subdivisions b and c of Division E of Part I of the Act. In this regard, the T2 Corporation Income Tax Guide … states that the Part I tax payable for the year is the basic Part I tax plus the amount of surtax, the amount of recapture of the investment tax credit, and the refundable tax on the Canadian-controlled private corporation’s investment income, minus any allowable deductions and credits, including the federal tax credit for forestry operations.

In light of the foregoing, it is our view that the expression "tax otherwise payable under this Part" for the purposes of subsection 127(1) includes the corporate surtax under section 123.2.