Deloitte Touche Tohmatsu announced Tuesday that its annual revenues were $27.4 billion, the sixth consecutive year the Big Four firm’s revenues have grown by a double-digit percentage.

The accounting firm said those results, aggregated from all its member firms for fiscal year 2008, represented a year-over-year increase of 18.6 percent. The firm also said it had added 15,000 employees to its ranks, for a total of 165,000 employees worldwide.

The largest single share of Deloitte’s revenue comes from its audit business, which grew 14.8 percent to $12.7 billion. The firm said its financial advisory services grew even faster, at 26.6 percent, to $2.4 billion, followed by consulting services, which grew 22.2 percent to $6.3 billion. Tax and legal services grew 20.4 percent to $6.0 billion.

Deloitte is the first of the Big Four to announce its annual revenues this year. In 2007, the Deloitte, and all the other Big Four firms, did not release results until the fall. Ernst & Young reported 2007 revenues of $21.1 billion, KPMG announced revenues of $19.8 billion, and PricewaterhouseCoopers reported revenues of $25.2 billion, with all three firms also boasting double-digit growth. Deloitte reported 2007 revenues of $23.1 billion.

The continued rising fortunes of audit firms is something of a sore spot for finance executives, though not necessarily a phenomenon those executives blame entirely on the firms themselves. In the wake of the Sarbanes-Oxley Act of 2002, costs skyrocketed as audits grew more complex and required testing of internal controls. More recently, complex accounting rules that increasingly rely on judgment-laden estimates of fair value also share some of the blame for audit cost hikes, say finance executives. “The complexity of these standards is worrying, and documenting and implementing them tend to drive up costs,” Johnson Controls CFO Bruce McDonald told CFO magazine in May.

In a survey of 205 senior finance executives in the May issue of CFO magazine, 82 percent said their audit costs had increased from 2007 to 2008, and 73 percent said they expected their audit costs to increase from 2008 to 2009. While a large majority of survey respondents (86 percent) said they were very satisfied or somewhat satisfied with their auditors, audit costs were the number one reason cited by the 14 percent who said they were dissatisfied.

The Americas region, which includes the United States, remains Deloitte’s biggest market, with revenues growing 12.9 percent to $13 billion. But the firm said its highest revenue growth, 30.3 percent, came in the Asia-Pacific region, which returned aggregate revenues of $3.2 billion. Europe, the Middle East, and Africa increased revenue by 22.6 percent to $11.3 billion, with Russia and the former Soviet states that make up the Commonwealth of Independent States growing at 40.8 percent. Deloitte audit firms in Brazil, Russia, India, and China have experienced 90 percent growth in the number of professionals it hires in the past three years.

Like all the other Big Four firms, Deloitte is not a public company and does not have to comply with U.S. GAAP when reporting its financial results. While all of the Big Four firms do historically announce their annual revenues, they do so in part to try to establish bragging rights over their rivals.

Deloitte’s revenue number, for example, includes reimbursed expenses, and the announcement noted that, “This financial summary reflects the aggregate of selected operating and financial data of the member firms and their subsidiaries and affiliates . . . and is not represented as nor considered to be the actual or pro forma financial results of any single member firm or entity, or group of member firms or entities prepared on a consolidated basis.”

Indeed, the announcement continues: “Such a consolidation would generally not be appropriate or permissible under international or local generally accepted accounting principles.” The announcement also notes that “although the member firms use a similar structure of financial accounts, certain items may be classified and reported differently by different member firms as a result of the varying accounting practices in their countries. Aggregate results do not attempt to reconcile or restate certain transactions that are reported differently among the member firms.”