The taxpayer advocate has a surprising amount of power. The advocate agents can rifle through the IRS computers at will, which makes them great at locating filings the IRS claims never occurred. The advocate can also stop collection efforts by the IRS and even release tax liens on your bank account or property. Basically, the advocate office is the place to go when you think you are getting a raw deal from the IRS.
The taxpayer advocate agents do not take any old case. In general, you have to show the IRS is unresponsive to your problem or causing you a major hardship. For instance, if your correspondence to the IRS is not being responded to, the advocate can crack the whip on your behalf. If the IRS puts a lien on your bank account, but you’re in the hospital, the advocated can release it. The advocate, however, does not give tax advice or fight audits for you.