Form 8821 and Form 2848 serve different purposes. Form 8821, Tax Information Authorization, allows a third party to access and inspect your tax information without the power to act on your behalf. Form 2848, Power of Attorney and Declaration of Representative, grants a tax professional or attorney the authority to represent you before the IRS and make decisions on your behalf. In short, Form 8821 offers limited access to your tax information, while Form 2848 provides broader authority for representation.