Amortisation of film production costs: provisional and class-based allowances guide assessments for producers and distributors. Guidance permits provisional assessments permitting estimated proportionate deductions of film production or distribution-rights costs against actual receipts when final receipts are unknown, with final adjustment after the exploitation period. Entire cost may be allowed if the film is fully exploited in the year of release; otherwise costs are apportioned over years by realised collections and estimated future receipts. High-cost films follow fixed multi-year amortisation percentages, while lower-cost films are generally treated as having one-year effective life; distributors are treated like producers and mixed exploitation requires proportionate outright deduction with balance amortised.