IT IS hardly news that the “Big Four” accounting firms get bigger nearly every year. But where they are growing says a lot about how they will look like in a decade, and the prospects worry some regulators and lawmakers. On September 19th Deloitte Touche Tohmatsu was the first to report revenues for its 2012 fiscal year, crowing of 8.6% growth, to $31.3 billion. Ernst & Young, PwC and KPMG will soon report their revenues (as private firms the Big Four choose not to report profits).

For all four, Asia is a bright region. Deloitte’s revenue in Asia grew by 16.3% in dollar terms, faster than anywhere else. This was despite long-running worries about dodgy audits of Chinese companies by Western firms. American and Chinese regulators have been rowing over whether America’s accounting watchdog may inspect Deloitte Shanghai’s work. The two sides recently announced that American regulators could visit and observe, but not perform their own inspections.

Yet more important, at all four firms consulting has been growing much faster than the audit business in recent years. In fiscal 2012 Deloitte increased its revenues from consulting by 13.5% and from financial advisory by 15%—compared with just 6.1% for audit and 3.9% for tax and legal services (see chart). Barry Salzberg, Deloitte’s boss, says he expects consulting to continue to grow by double digits, whereas the audit market is mature. Deloitte is adding consulting staff at twice the rate as employees for audits (at the end of May the firm had 193,000 people on its payroll). If the two businesses continue to grow at the 2012 rate, the firm would do more consulting than auditing by 2017. Some lawmakers already fret that consulting and tax advisory (when the Big Four are explicitly helping companies make money) can be in conflict with auditing (where the firms should take a wary, outside view of the books, in the service of investors not management). Lynn Turner, a former chief accountant at America’s Securities and Exchange Commission, calls the audit firms a “public utility”, but worries that they do not see themselves that way. In 2002 the Sarbanes-Oxley act limited what kind of non-audit services an American accounting firm can offer to an audit client. But contrary to what many people believe, it did not forbid all of them. In its last full proxy statement before being bought by JPMorgan, Bear Stearns reported paying Deloitte in 2006 not only $20.8m for audit, but $6.3m for other services. The perception that auditors and clients are hand-in-glove, fair or not, is a reason why shareholders of Bear Stearns sued Deloitte along with the defunct bank. (JPMorgan and Deloitte settled in June. Deloitte paid out $20m, denying any wrongdoing.) The European Commission in Brussels recently proposed taking a meat-axe to the problem. A draft directive provides for the creation of audit-only firms in the European Union. But the legal-affairs committee of the European Parliament does not like the idea. With the EU’s legislative machinery slow and complex, it is impossible to predict the final outcome.

Asked what would happen if people perceived Deloitte as a consulting firm with an audit business rather than the other way round, Mr Salzberg replies: “we’re not going to take our eye off our professional responsibility with respect to either.” The future of the Big Four’s business model may depend on whether lawmakers in Europe and America are convinced that this is possible.