Natural Catastrophe Insurance Act of 2005

Natural Catastrophe Insurance Act of 2005 - Directs the Secretary of the Treasury to carry out a program to make reinsurance coverage available for purchase only by eligible State programs.

Requires a reinsurance contract to cover residential and business property losses insured or reinsured by the eligible State program and proximately caused by windstorm, earthquake, winter catastrophe, fire, tsunami, flood, volcanic eruption, or hail.

Establishes within the Treasury the Disaster Reinsurance Fund to pay for the administrative expenses of the reinsurance program.

Requires the Secretary to study and report to Congress annually on the cost and availability of insurance for losses resulting from catastrophic disasters covered by the reinsurance program under this Act.

Requires the Comptroller General to study and report to Congress on: (1) the need for a federal program to provide reinsurance for insured losses resulting from any catastrophe event that may threaten the solvency of any segment of the catastrophe insurance industry; and (2) the appropriateness of such a program to stabilize financial and insurance markets, and ensure the availability and affordability of insurance in the United States for losses from such events.