In response to a call for more comparable reporting of audit profitability from the Financial Reporting Council, guidance has been published for audit firms on the voluntary disclosure of the financial results of their work on statutory audits and directly related services. The Voluntary Code of Practice on Disclosure of Audit Profitability, published by the Consultative Committee of Accountancy Bodies, takes effect for accounting periods beginning on or after 6 April and applies to any UK 'major' audit firm, according to criteria laid down by the Professional Oversight Board. Any firm that carries out over ten audits of public interest entities is defined as a 'major' firm according to the POB. In March 2009 there were nine of these. Major firms are subject to full-scope inspections by the Audit Inspection Unit. By requesting the code, the FRC aims to achieve greater consistency in the definition of the audit segment and the way the firms allocate overheads to that segment in their published financial reports. The code states that the reported audit section should include all the fees incurred for any statutory audit (not just companies) plus the fees in respect of that work that 'fits naturally' with the auditor's statutory responsibilities, which is work that will be or is being carried out by the auditor. It also says that overheads that are measured and recognised in the firm's financial statements should be allocated to the reportable segment and the impact of material non-recurring income and costs should be disclosed so that their effect on profitability can be highlighted. Working group chairman Andrew Vials said that the principles-based code will lead to 'improved transparency in reporting by audit firms, and enhanced comparability when considering the profitability of the statutory audit segment'. Disclosure can be applied in either the firm's transparency report or in its annual report.