Tonnage tax scheme: deemed tonnage income treated as business profits, excluding actual shipping income under eligibility conditions.
Clause 226(7) mandates that tonnage income be computed under a separate formulaic provision and be deemed to be the profits chargeable under business income, while expressly excluding the actual "relevant shipping income" from tax once the tonnage computation applies; these effects are conditional on compliance with the Part's eligibility, option, separation, and record keeping requirements.

Tonnage tax scheme: elective presumptive taxation for shipping income, requiring separate accounting and exclusive computation under qualifying criteria.
The tonnage tax scheme is an elective presumptive regime requiring eligible companies operating qualifying ships to compute profits from that business exclusively under the tonnage basis; the tonnage tax business is treated as a separate business with independent computation and accounting, and companies not opting or ineligible must compute shipping profits under the normal provisions of the Act.

Tonnage tax eligibility defined by operation status: owners and charterers qualify, long term bareboat lessors excluded.
Clause 226(1) treats a company as operating a ship or inland vessel if it owns or charters a vessel, including partial charters such as slot, space, or joint charters, and excludes companies that have chartered out vessels on bareboat charter or bareboat charter cum demise terms for periods exceeding three years, thereby distinguishing operational risk bearing operators from passive, long term financiers for purposes of the tonnage tax scheme.