How is "corporation tax" defined according to the context?
According to the context, "corporation tax" is defined as any tax on income that is payable by companies and fulfills certain conditions: (a) it is not chargeable in respect of agricultural income; and (b) no deduction in respect of the tax paid by companies is, by any enactments which may apply to the tax, authorised to be made from dividends payable by the companies to individuals.