If the representative is to appear before the IRS without the taxpayer, a Power of Attorney will be necessary. Ideally an IRS Power of Attorney will be used (form 2848). This document contains specific legal disclosure that the representative agrees to abide by, including but not limited to: Being aware of regulations contained in Treasury Department Circular No. 230 and not being under suspension or disbarment.
In the case that a non-IRS power of attorney is used, a copy of form 2848 will have to be attached to it and signed by the representative.
A representative may also be authorized to receive confidential information without providing representation, in which case a Power of Attorney is not necessary, this can be achieved by filing a form 8821, Tax Information Authorization.