Set off and carry forward of losses: losses from owning race horses only offset against same-activity income, with limited carryforward. Losses from the activity of owning and maintaining race horses may be set off only against income from that specified activity; any unabsorbed loss is carried forward to subsequent tax years to be set off against income from the same activity until exhausted. The carry forward is limited by a statutory temporal cap. Definitions provided clarify that allowable loss equals the deficit of stake money over non-capital expenditure wholly and exclusively incurred for maintaining race horses, and that 'specified activity' means owning and maintaining race horses.