Tonnage taxation: daily tonnage income per ship is aggregated and taxed as business profits under corporate rates. Determine each qualifying ship's certified net tonnage (including prescribed deemed tonnage), convert that tonnage into a daily tonnage income under the slabbed per 100 ton rates, multiply by the number of days each ship was operated, and aggregate all ships' tonnage incomes; the aggregate is treated as profits from business and is taxed at the prevailing corporate tax rate. Tonnage is rounded to the nearest hundred tons per the prescribed rule and no deduction or set off is allowed in computing tonnage income.