The proposal addresses economic and governance issues in the country, including reforming the judiciary.
The funds would be needed for "reconstructing the state and the economy in the service of all Haitians," the report said.
The report was published two months after the January 12 earthquake killed more than 220,000 people in Port-au-Prince and its surrounding towns and villages.
"The earthquake has created an unprecedented situation, amplified by the fact that it struck the country's most populous region and its economic and administrative centre," the report said.
"The total amount of money needed stands at $11.5bn and breaks down like this: 50 per cent for the social sector, 17 per cent for infrastructure including housing, and 15 per cent for the environment and disaster risk management," it said.
However, Patrick Delatour, Haiti's tourism minister, said that the actual figure needed could end up being anything between $8bn and $14bn.
The 7.0 magnitude earthquake caused damage of more than $7.9bn - about 120 per cent of the country's gross national product (GDP) - according to the report.
About 70 per cent of those losses were attributed to the private sector while $4.4bn of damage was to public buildings and infrastructure.
The government said in the report that they would develop infrastructure and new economic opportunities outside Port-au-Prince and decentralise power during the reconstruction process.