Internal Revenue Service: Exempt Organization Search — Provides search engine for identifying tax exempt organizations.
IRS Forms & Publications — Links to tax forms, instructions and publications (selected); includes links to tax notices, direct FTP connection, and state tax forms.
State Tax Rates & Structure — State tax rates, state taxation of social security/pensions, state sales and excise tax rates and tax-related surveys.
The Tax Prophet — Searchable collection of tax information edited by Robert L. Sommers.
Transactional Records Access Clearinghouse IRS Site — Nonpartisan data about the Internal Revenue Service (IRS), national profile and trends, enforcement policies and practices.