Reserve for unexpired risks capped by net premium income for insurance businesses, with specific limits by policy class. Limits are prescribed for the amount that may be carried to a reserve for unexpired risks in computing profits and gains of business of insurance other than life insurance. The reserve, including any additional reserve deductible under the First Schedule, is capped by reference to the net premium income of the previous year, with different ceilings for fire, engineering, miscellaneous, and marine insurance. Amounts not allowed as a deduction are not included in total income for the immediately succeeding assessment year. Net premium income is premium received less reinsurance premium paid.