Carry forward of business losses requires timely filing and permits adjustment only against business income under the tax code. Carry forward of business losses (other than speculative business) is permitted only if the return for the year of loss is filed on or before the due date; such losses may be adjusted only against income under the head 'Profits and gains of business or profession' and can be carried forward for eight immediately succeeding years. Special rules restrict set off and carry forward of losses from specified incentivised businesses to income from those businesses (with unlimited carry forward subject to return filing requirements) and confine racehorse business losses to set off only against racehorse income with a shorter carry forward period.