(1) Where a tonnage tax company also carries on any business or activity other than the tonnage tax business, common costs attributable to the tonnage tax business shall be determined on a reasonable basis.
(2) Where any asset, other than a qualifying ship, is not exclusively used for the tonnage tax business by the tonnage tax company, depreciation on such asset shall be allocated between its tonnage tax business and other business on a fair proportion to be determined by the Assessing Officer, having regard to the use of such asset for the purpose of the tonnage tax business and for the other business.