These forms and publications discuss who can represent a taxpayer before the IRS and what forms and documents are used to authorize a person to represent a taxpayer.
Form 2848 - Power of Attorney and Declaration of Representative
Use Form 2848 to authorize an individual to represent you before the IRS. The individual you authorize must be a person eligible to practice before the IRS.
Form 8821 - Tax Information Authorization
Form 8821 authorizes any individual, corporation, firm, organization, or partnership you designate to inspect and/or receive your confidential information in any office of the IRS for the type of tax and the years or periods you list on Form 8821.
Publication 947 - Practice Before the IRS and Power of Attorney
This publication discusses who can represent a taxpayer before the IRS and what forms or documents are used to authorize a person to represent a taxpayer.
Publication 4019 - Third Party Authorizations
There are various methods by which third parties may be granted authority to assist taxpayers in resolving tax issues. Publication 4019 contains a chart that identifies the products available for addressing a taxpayer's specific needs and the means of submitting an authorization. All of the products allow for the exchange of information with the IRS for purposes of resolving a tax issue.