Tonnage tax loss set off limited to shipping income; pre option losses deemed set off and apportionment must be reasonable.
Clause 230(2)-(4) (and mirror Section 115VM) deem pre option losses attributable to the tonnage tax business to have been set off against relevant shipping income while under the tonnage tax regime, bar their set off against non shipping income after opting in, and require any necessary apportionment to be made on a reasonable basis, creating documentary and evidentiary obligations and potential disputes over apportionment and the definition of relevant shipping income.

Tonnage tax exclusion: carry forward and deductions barred, creating a self contained computation regime for shipping companies under new bill
Clause 230(1) creates a self contained tonnage tax computation by deeming all business losses, allowances and deductions to have been given full effect in their year of origin, prohibiting carry forward or set off of shipping business losses once under the tonnage regime, excluding general chapter based deductions from tonnage profits, and requiring written down values of assets to be computed as if depreciation had been claimed and allowed each relevant year.