Duple Motor Bodies Ltd v Inland Revenue Comrs (Inland Revenue Comrs v Duple Motor Bodies Ltd, Ostime v Duple Motor Bodies Ltd)

In computing taxable trading profits, stock-in-trade and work in progress must be valued consistently with ordinary commercial accounting, so far as applicable, and in conformity with income tax law. No single costing method governs every business.

A long-established direct-cost method cannot be displaced by an imprecise allocation of overheads without sufficient justification. General business expenditure ordinarily lies where it falls and is deductible in the year incurred, subject to statutory exclusions. A valuation method must not shift deductible expenditure into work in progress or inflate taxable profit merely because reduced production increases the overhead attributed to each unfinished article.

The company manufactured motor vehicle bodies, principally to individual order. Its unfinished bodies were valued by the direct-cost method, which principally included attributable labour and materials. The Crown assessed its income tax under Case I of Schedule D of the Income Tax Act 1952, and related profits tax, by requiring an on-cost method which allocated a proportion of factory overheads to work in progress.

The Special Commissioners upheld the assessments but stated a case. Vaisey J reversed their determination, and the Court of Appeal affirmed his decision. The Crown's consolidated appeals asked whether the Commissioners had erred in law by requiring the on-cost method when computing the company's profits.

1. Disposition. The House unanimously dismissed the consolidated appeals and affirmed the Court of Appeal's orders. Lord Reid delivered the reasoning expressly adopted by Lord Tucker and Lord Hodson. Viscount Simonds and Lord Guest delivered concurring speeches.
2. The governing approach. Per Lord Reid, the court must determine what figure fairly represents the cost of stock-in-trade and work in progress in the circumstances of the particular business. Ordinary commercial accounting carries great weight, but the court has the final word. The method must also conform to income tax law. No hard-and-fast costing rule can resolve every case.
3. Consistency and change of method. Per Lord Reid, a valuation method must be applied consistently. A method consistently used in earlier years should not be changed without a good reason sufficient to outweigh the difficulties created in the transitional year. The case disclosed no justification for compelling this company to abandon direct cost, although particular directly attributable items, such as power used on unfinished bodies, might require inclusion.
4. Annual expenditure. Per Lord Reid, business expenditure allowable under Income Tax Act 1952, section 137, is brought into account in the year incurred even if it is abortive, relates to future production, or cannot be matched with particular receipts. The relevant question was therefore what expenditure could properly be represented by stock or work in progress, rather than what expenditure should be left against goods already sold. Lord Guest similarly concluded that the proposed on-cost method would indirectly disallow expenditure otherwise deductible under section 137.
5. Rejection of compulsory on-cost valuation. Per Lord Reid, the accountancy evidence recognised both methods and disclosed numerous undefined variations of on-cost accounting. It supplied no principled basis for requiring factory overheads while excluding other overheads. The method could also inflate profit during slack trading because fewer articles bore a greater share of overheads. That feature made a demonstrated justification especially necessary, and none existed.
6. Concurring reasoning. Viscount Simonds considered the stated question incapable of a precise answer because the on-cost method was undefined. He nevertheless rejected its compulsory imposition and emphasised that a taxpayer should not risk assessment on profit exceeding what could be determined with reasonable certainty. Lord Guest held that direct cost satisfied both ordinary accounting practice and the requirements of the taxing legislation. The Crown had failed to establish that on-cost accounting was universally required.

1. House of Lords: The consolidated appeals were dismissed, and the Court of Appeal's orders were affirmed. The appellants were ordered to pay the respondent's costs.
2. Court of Appeal: The court affirmed Vaisey J's reversal of the Special Commissioners. It held on the facts and figures that the on-cost method produced an unfair result and that direct cost was appropriate.
3. High Court: Vaisey J reversed the Special Commissioners' determination. The Court of Appeal later affirmed the result while declining to approve his ground of decision.
4. Special Commissioners: The Commissioners upheld the assessments based on an on-cost method but stated a case for the court's opinion.