National Long Distance operations qualify as an independent...

National Long Distance operations qualify as an independent undertaking for deduction where separately licensed infrastructure, dedicated resources, and separately identifiable revenue and expenditure establish a commercially distinct unit; an independent accountant's prescribed audit certificate suffices. Computer-integrated switches may fall within the computer block, while obsolete assets remain depreciable where the business block continues in use. Interest from temporary deployment of circulating business funds is business income. No additional exempt-income disallowance arises where no exempt income is earned, although a voluntary disallowance remains if its computation is not shown erroneous. Goodwill from business acquisition is a depreciable intangible asset, refund interest runs until actual payment, and transfer-pricing charges require comparable-based, currency-specific benchmarking.