国会研究服务部-国家洪水保险方案：现行等级结构和风险等级2.0（英文）-2021.6-19页_1mb

Summary of the National Flood Insurance Program: The Current Rating Structure and Risk Rating 2.0

Introduction

The National Flood Insurance Program (NFIP), established in 1968, is the primary source of flood insurance coverage for residential properties in the U.S., with over five million policies in 22,500 communities across 56 states. It generates approximately $4.6 billion in annual revenue and provides over $1.3 trillion in coverage. The program aims to provide flood insurance to high-risk properties and reduce flood risk through floodplain management. A long-term goal is to reduce federal disaster assistance costs.

Current Rating Structure

The current NFIP rating system, unchanged since the 1970s, classifies properties based on:

• Flood zone (from Flood Insurance Rate Maps or FIRMs)
• Occupancy type (e.g., single-family, nonresidential)
• Elevation relative to Base Flood Elevation (BFE)

FEMA groups similar properties and assigns the same rate to all within a group, regardless of their specific location or topography. This approach results in cross-subsidies, where properties in lower-risk areas subsidize those in higher-risk areas.

Key Components of Premiums

• Federal Policy Fee (FPF): Covers administrative costs. Rates vary by policy type.
• Reserve Fund Assessment: Maintains a reserve for future claims and debt, initially at 15% and later increased to 18% of the premium.
• HFIAA Surcharge: Additional charge based on property type (25 for primary residences, 250 for others).
• Increased Cost of Compliance (ICC) Coverage: Required for most policyholders to cover compliance costs with stricter building codes, up to $30,000, capped at $75.

Subsidies and Cross-Subsidies

There are three main subsidy categories:

1. Pre-FIRM Subsidy: For properties built or improved before the first FIRM was published (December 31, 1974). These properties are charged less than the actuarial rate. As of September 2018, 13% of policies received this subsidy.
2. Newly Mapped Subsidy: For properties newly mapped into a Special Flood Hazard Area (SFHA) after April 1, 2015, and insured within a year. These policies pay the Preferred Risk Policy (PRP) rate for the first 12 months, with annual increases of 15%. About 4% of policies received this subsidy.
3. Grandfathering: Allows properties that were built in compliance with an earlier FIRM to retain their old rate class if remapped. This is not considered a direct subsidy but is cross-subsidized. About 9% of policies were grandfathered as of September 2018.

Risk Rating 2.0: Proposed Changes

Risk Rating 2.0 represents the most significant change to NFIP premium calculation since its inception, introducing more accurate and individualized flood risk assessments. Key changes include:

• Premiums Based on Actual Flood Risk: Rates will be tied to specific property characteristics rather than flood zones.
• New Flood Risk Sources: Incorporates pluvial flooding, tsunami, Great Lakes flooding, coastal erosion, and flooding in leveed areas.
• Use of Catastrophe Models: FEMA will use three commercial models to estimate future loss potential, including probability, intensity, damage, and loss allocation.

New Variables Used

• Geographical Variables: Distance to water, type of water (river, lake, coast), drainage area, and proximity to barrier islands or levees.
• Structural Variables: Foundation type, lowest floor height relative to BFE, and replacement cost value.
• Mitigation Credits: Discounts for properties with flood protection measures, such as levees or elevation.

Flood Zones in Risk Rating 2.0

While flood zones will no longer directly influence premium calculations, they will still be used for floodplain management and the mandatory purchase requirement for federally backed mortgages.

Rate Increases and Statutory Limits

• Annual premium increases for primary residences are capped at 5%–18%.
• Risk Rating 2.0 will not increase rates faster than these limits.
• The new rates will apply to new policies starting October 1, 2021, and to existing policies starting April 1, 2022.

Impact and Observations

• FEMA conducted probabilistic flood risk analyses and validated results using historical NFIP data.
• The new model focuses on complex flood hazards and levee quality, providing more detailed and accurate risk assessments.
• The goal is to reduce federal subsidies and make the NFIP more sustainable and equitable.

Conclusion

Risk Rating 2.0 aims to modernize the NFIP by aligning premiums with actual flood risk, incorporating advanced modeling techniques, and reducing cross-subsidies. While it introduces more complexity in terms of variables, it is expected to improve the accuracy and fairness of flood insurance pricing, ultimately making the program more financially sustainable.