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Data updated October 22, 2026

Data updated October 22, 2026

Shaded Zone X flood zone: the 0.2% annual chance floodplain

Updated October 22, 2026

Shaded Zone X, labeled Zone B on older maps, is FEMA's moderate flood hazard zone: mainly the land between the 1% and 0.2% annual chance (100-year and 500-year) floodplains. It is outside the Special Flood Hazard Area, so federal law does not require flood insurance there.

Shaded Zone X is the middle category on a Flood Insurance Rate Map (FIRM): more flood hazard than unshaded Zone X, less than the Special Flood Hazard Area (SFHA). In most places it is the band of land that a 0.2% annual chance flood would reach but a 1% annual chance flood would not.

What shaded Zone X means

FEMA’s flood zone glossary states: “Moderate flood hazard areas, labeled Zone B or Zone X (shaded) are also shown on the FIRM, and are the areas between the limits of the base flood and the 0.2-percent-annual-chance (or 500-year) flood.” 44 CFR 64.3 lists “B, X” as “Areas of moderate flood hazards or areas of future-conditions flood hazard.”

The moderate category is wider than the 500-year band. FEMA’s FloodSmart zone page says B zones “are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100-year floods, or shallow flooding areas with average depths of less than 1 foot or drainage areas less than 1 square mile.” In other words, shaded Zone X can include:

  • land between the 1% and 0.2% annual chance floodplains;
  • areas of 1% annual chance shallow flooding with average depths of less than 1 foot;
  • areas of 1% annual chance flooding where the drainage area is less than 1 square mile;
  • areas protected from the 1% annual chance flood by levees;
  • future-conditions flood hazard areas, which 44 CFR 64.3 allows on a FIRM at the community’s request.

FEMA’s shallow flooding mapping guidance (December 2020) sets limits on the last two shallow cases. Shaded Zone X is used for shallow flooding only when the average depth across the whole flooded area is less than 1.0 foot. The drainage area rule applies in a new study where no effective SFHA exists, when the contributing area is under 1.0 square mile and there is no history of destructive flooding or significant potential for damage to future development. Existing SFHAs may be removed only on the depth criterion.

On FEMA’s digital maps, the 0.2% band appears as Zone X with the subtype “0.2 PCT ANNUAL CHANCE FLOOD HAZARD”, which is why it is often called X500. Levee-protected areas have their own subtype. Read the map legend or the zone subtype to know which kind applies.

Is flood insurance required in shaded Zone X?

No federal requirement applies. 42 U.S.C. 4012a requires flood insurance on loans from federally regulated lenders, loans bought by Fannie Mae or Freddie Mac, and federal financial assistance only for buildings in the SFHA (Zones A, AE, AH, AO, AR, A99, V and VE). 44 CFR 64.3(b) does not list Zone B or X among the mandatory purchase zones. NFIP policies are available in participating communities. See flood insurance requirements for what changes if a map revision moves a building into the SFHA.

Building rules in shaded Zone X

The federal elevation standards in 44 CFR 60.3 are written for A and V zones, which have base flood elevations or depths. Shaded Zone X has neither on the FIRM, so the regulation sets no elevation requirement there. Local floodplain ordinances and building codes still apply.

What shaded Zone X means for insurance cost

FEMA states that the NFIP’s pricing approach under Risk Rating 2.0 “does not use flood zones” to determine flood risk. Premiums reflect flood frequency, flood types, distance to water, elevation and rebuilding cost, so a building’s position in shaded or unshaded Zone X does not by itself set the price.

How to check a parcel’s zone

Search the address on FEMA’s Flood Map Service Center for the effective FIRM and any Letters of Map Change, and look at the shading and legend. A building in shaded Zone X next to an AE or AH boundary sits close to the SFHA line, so check where the structure itself falls.

Shaded Zone X in Miami-Dade County

Miami-Dade’s effective FIRM, in the July 2026 snapshot of FEMA’s National Flood Hazard Layer we use, maps shaded Zone X only as the 0.2% annual chance flood hazard subtype; it has no levee-protected X areas. Of the about 551,600 buildings in Miami-Dade’s 80 ZIP code areas (78 with reports), 32,283 (5.9%) have their centroid in shaded Zone X, based on FEMA/ORNL’s USA Structures inventory. The ZIPs with the most:

New Miami-Dade FIRMs take effect on February 19, 2027 (91 FR 65238). A parcel’s zone can change on that date; see the 2027 Miami-Dade flood maps and unshaded Zone X for comparison.

Questions

Is flood insurance required in shaded Zone X?

Not by federal law. The mandatory purchase requirement in 42 U.S.C. 4012a applies to the Special Flood Hazard Area, and shaded Zone X is outside it. NFIP policies are available there in participating communities.

What is the difference between shaded and unshaded Zone X?

Shaded Zone X (formerly Zone B) is a moderate flood hazard area, mainly between the 1% and 0.2% annual chance floodplains. Unshaded Zone X (formerly Zone C) is a minimal hazard area, outside the SFHA and higher than the 0.2% annual chance flood.

What does X500 mean?

X500 is an informal name for shaded Zone X in its most common form, the 0.2% annual chance (500-year) flood hazard area. On FEMA's digital maps it is Zone X with the subtype 0.2 PCT ANNUAL CHANCE FLOOD HAZARD.

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