In his second report criticizing the Internal Revenue Service this week, the U.S. Treasury Department's inspector general said the agency's contractor employees owe millions of dollars in back taxes — even though its own workers must submit their tax payments on time.

The report, released Wednesday, said that nearly 700 IRS contractor employees, or 5 percent of the agency's total, owed $5.4 million in federal tax debt. More than half of those individuals were not on a payment plan to resolve their obligations.

"Because many contractor employees have access to sensitive IRS systems and facilities, the IRS should address tax noncompliance for these employees in similar manner as it would for its own employees," said J. Russell George, inspector general for tax administration.