BDO Seidman said its revenue for the fiscal year ended June 30 fell 5.9 percent to $620 million from last year’s revenue of $659 million.

However, the firm said its tax business line experienced revenue growth of 6 percent. BDO’s assurance business fell 9.1 percent and its BDO Consulting business decreased 15.3 percent from last year’s high. Over the past four fiscal years, BDO Seidman has averaged double-digit growth of 10.2 percent.

The firm blamed the recession for the revenue decline, even though billable hours have remained steady. “After several years of strong revenue growth, BDO Seidman — like most businesses — was negatively impacted by the protracted economic recession in fiscal 2009,” said BDO Seidman CEO Jack Weisbaum in a statement. “Fortunately, the firm’s billable hours remained comparable to the previous fiscal year, as we continue to work with our clients in helping them through this difficult time, and we believe we are well positioned for a return to revenue growth as the economy recovers.”

The assurance business line represents 60 percent of BDO Seidman’s business. The firm’s tax and BDO Consulting business lines represent 25 percent and 10 percent of revenues, respectively. Other services such as real estate, wealth management and software sales account for the remaining 5 percent.