The GAO found a few problems auditing the IRS

These control deficiencies are:

nationwide strategy for safeguarding taxpayer receipts and associated information, 
physical security policies and procedures, 
review of visitor access logs, 
transmission of taxpayer receipts,
 designations of unit security representatives, 
review of automated tax refund information prior to certification for payment, 
review of refund schedule numbers for manual refunds, 
and review of suspicious and questionable tax returns in Examination.