The apparently arbitrary allocation of many costs in conventional accounting ‘matching’ practice is a long-standing, unresolved and potentially important problem. Thomas (1974) argued that all matching-based allocations are ‘incorrigible’. This paper discusses the issues and proposes modifications to, and interpretations of, current practice that attempt to alleviate the problem. The analysis proposes an incremental development, rather than the introduction of very radical proposals. Consequently it proceeds on the basis of the generally accepted accounting principles of conventional accounting, which may be expected to reflect the perceptions of practitioners and are incorporated in company law.