CANBERRA, July 2 -- Three years ago, Australia's government treated the PwC tax leaks scandal as an outlier, a single firm that had crossed a line. On Wednesday, Treasury made clear it now treats the entire structure of the Big Four as the problem.

Assistant Treasurer Daniel Mulino released a consultation paper proposing to bring Deloitte, EY, KPMG and PwC under the direct purview of the Australian Securities and Investments Commission for the first time, a jurisdictional expansion that would let the regulator act against the firms themselves rather than only the individual auditors registered within them. Reuters reported Mulino saying, "In recent years, we have seen behaviour from some large accounting, auditing and consulting firms in...