Zone A and Zone AE are both high-risk FEMA flood zones inside the Special Flood Hazard Area. Both carry a 1% annual chance of flooding (the 100-year floodplain). Both require flood insurance for federally backed mortgages. The fundamental flood risk is the same.
The difference is precision of information. Zone AE has Base Flood Elevations determined — FEMA has conducted detailed hydraulic engineering analysis to calculate exactly how high floodwaters will rise at specific locations. Zone A does not — FEMA has identified the area as high-risk but hasn't done the detailed study needed to establish BFEs.
| Feature | A Zone A | AE Zone AE |
|---|---|---|
| Annual flood probability | 1% (100-year) | 1% (100-year) |
| Inside SFHA? | Yes | Yes |
| Insurance required (federal mortgage)? | Yes | Yes |
| Base Flood Elevation on map? | No | Yes |
| Elevation Certificate impact on premium | Indirect (no BFE to compare) | Direct (elevation vs. BFE) |
| Where typically found | Rural, less-studied areas | Developed, urban areas |
| Predecessor zones | Replaced older unnumbered A | Replaced A1-A30 numbered zones |
The BFE is the calculated water surface elevation during the 1% annual chance flood at a specific location. It appears on Flood Insurance Rate Maps as a contour line with an elevation in feet above sea level (or sometimes above NAVD 88 datum).
For Zone AE properties, the BFE is central to three things:
Insurance pricing. Under NFIP, how high your first floor sits relative to the BFE directly affects your premium. Being two feet above the BFE can reduce annual premiums by $1,000 or more compared to being at BFE. Being below BFE increases premiums significantly. For Zone A properties, without a BFE, insurers have to make assumptions — which often means less favorable pricing.
Building requirements. New construction and substantial improvements in Zone AE must have the lowest floor at or above the BFE (plus a freeboard that many communities require — often one foot above BFE). In Zone A without a BFE, communities must still require elevation but have more flexibility in how to determine the required elevation.
LOMA eligibility. To get a Letter of Map Amendment removing your property from the SFHA, the key showing is that your land is at or above the BFE. In Zone AE, the BFE is right there on the map. In Zone A, a hydraulic study may be needed to establish what the BFE would be.
Under NFIP's Risk Rating 2.0, both Zone A and Zone AE properties can obtain Elevation Certificates to document their first-floor height — and both can benefit from elevation relative to the flood risk. The difference is in how precisely that benefit can be quantified.
For Zone AE: your Elevation Certificate compares your lowest floor to the BFE. One foot above BFE is a standard benchmark that qualifies for significantly reduced rates.
For Zone A: without a published BFE, FEMA uses an estimated BFE (derived from the best available data) for rating purposes. This can mean more variability in quotes and may require additional analysis to optimize your rate.
In both zones, Preferred Risk Policies are not available — those are reserved for lower-risk zones. Both zones use the standard NFIP rating structure for high-risk properties.
Use our address lookup to see your property's exact flood zone designation. The FEMA National Flood Hazard Layer data will tell you whether you're in Zone A, Zone AE, or any other designation.
If you're in Zone AE, your Flood Insurance Rate Map will show BFE contour lines. You can use FEMA's Map Service Center to view your FIRM panel and identify the BFE at your property location.
If you're in Zone A and want to know what a BFE would be for your property (for LOMA purposes or insurance rating), a licensed surveyor or civil engineer can conduct an analysis. Some Zone A areas have approximate BFEs in the FEMA study — it's worth checking before commissioning new work.
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