Stealth Lobbyist Disclosure Act of 2005

Stealth Lobbyist Disclosure Act of 2005 - Amends the Internal Revenue Code to treat as a tax-exempt political organization for purposes of the disclosure and other requirements applicable to such organizations (with certain modifications) any coalition or association that is identified as a client on any registration filed under the Lobbying Disclosure Act of 1995 and that is not a political organization.

Requires any such coalition or association to notify the Secretary of the Treasury of: (1) its existence within 72 hours after one of its lobbyists makes an initial contact; and (2) any change in membership within 72 hours. Requires such notice to include a general description of the business or activities of each member of the coalition or association and the amount reasonably expected to be contributed by each member toward coalition or association activities of influencing legislation. Imposes a penalty tax for failure to give required notices.

Exempts from the disclosure requirements imposed by this Act: (1) public charities and other tax-exempt organizations which have substantial exempt activities other than lobbying; and (2) members of a coalition or association who contribute less than $2,000 per year for lobbying activities.