"Generally, Google and companies of similar size are audited every year. Thus, the IRS actually has a permanent office within the Googleplex compound because they audit them year-round"
I think this statement is incorrect. The auditors hired (PwC, Deloitte, E&Y, whoever) are at the Googleplex all year round, but not the IRS
I misspoke, I stated auditors but I wasn't specific about his. Pwc, deliotte and friends are financial auditors meant to provide assurance. But the IRS auditors are there for tax audits.
It is IRS policy to generally audit fortune 500 companies annually. Usually they hold an area for the IRS because it makes sense for them to be kept away from daily operations. A former coworker works in the LMSB dept that handles these cases.
When the IRS starts printing special forms for you because the lines don't fit your revenues, you know you've made it lol.