Terrorism Insurance Act - Authorizes the Secretary of Commerce to require each commercial insurer to submit to the Secretary or the National Association of Insurance Commissioners (NAIC) a statement specifying the aggregate premium amount of coverage written for properties and persons in the United States under each line of commercial property and casualty insurance sold during specified periods.

Directs the Secretary to provide financial assistance to commercial insurers to cover insured losses resulting from acts of terrorism, conditioned upon payment of a terrorism loss repayment surcharge collected by such insurers and remitted to the Secretary.

Permits extension of this Act to self-insurance arrangements by municipalities and other public entities.

Expresses the sense of Congress that: (1) NAIC, in consultation with the Secretary, should develop appropriate definitions for acts of terrorism and appropriate standards for making determinations regarding such acts; (2) each State should adopt those definitions and standards for purposes of regulating insurance coverage; and (3) after consultation with the NAIC, the Secretary should adopt definitions for acts of terrorism and standards for determinations appropriate for this Act.

Expresses the sense of Congress that the States should require separate disclosure by insurance companies of the price of any terrorism coverage, including the costs of any terrorism related assessments or surcharges under this Act.