Flood zones B and C

Checked against FEMA and other official sources · Last reviewed October 8, 2026

What zones B and C mean

Federal regulations list both zones next to zone X. One line reads "B, X Areas of moderate flood hazards or areas of future-conditions flood hazard." The next reads "C, X Area of minimal hazards."

FEMA's glossary gives more detail:

• Zone B: "Area of moderate flood hazard, usually the area between the limits of the 100-year and 500-year floods." FEMA adds that B zones are also used for "base floodplains of lesser hazards." Examples are areas protected by levees from the 100-year flood, shallow flooding with average depths under one foot, and drainage areas under 1 square mile.
• Zone C: "Area of minimal flood hazard, usually depicted on FIRMs as above the 500-year flood level." FEMA notes that zone C "may have ponding and local drainage problems that don't warrant a detailed study or designation as base floodplain."

Both are outside the high-risk Special Flood Hazard Area. FEMA's map-reading guide calls them "Non-Special Flood Hazard Areas," shown "as zones beginning with the letters B, C, or X." To learn what the 100-year flood means, see what a 100-year flood means. [1][5][8][9]

B and C on newer maps: shaded and unshaded zone X

A FEMA fact sheet for coastal builders says it plainly: "Older FIRMs label X zones as zone 'B' or zone 'C.' Treat the old and new zone designations the same." (FIRM stands for Flood Insurance Rate Map.)

The match-up, in FEMA's glossary wording:

• Zone B = shaded zone X. Moderate flood hazard areas are "labeled Zone B or Zone X (shaded)."
• Zone C = unshaded zone X. Minimal flood hazard areas are "labeled Zone C or Zone X (unshaded)."

The NFIP's Flood Insurance Manual (April 2021) says the same: "Zone X equals the designation for B and C zones on some maps." It groups B, C and X together as areas "of moderate or minimal flooding hazard resulting from severe storm activity or local drainage problems." For more on how X is drawn today, see flood zone X. [2][3][4]

Why some maps still show B and C

Your zone comes from the flood map in effect for your community, and each map shows its own effective date. FloodSmart says FEMA and the NFIP "update the flood maps periodically." When FEMA issues a countywide map, the NFIP manual says it supersedes "all previous versions of the FEMA flood hazard maps for covered communities."

You may also come across old maps that have been replaced. One example is the City of North Port, Florida. The city says its flood maps were first created by FEMA in 1981 and 1984, and that those maps have been revised, with new maps effective Nov. 4, 2016. The city still offers the old 1981/1984 maps for download, and the same page defines zones B and C. If you're looking at an old map like these, check which map is in effect now.

One special case: in communities with unpublished maps, where local flooding is too small to map, the NFIP "considers all areas within these communities in the Regular Program as Zone C or X."

To find the map in effect for your address, see what flood zone am I in?. FloodSmart suggests you "check annually." [4][10][11]

Is flood insurance required in zone B or C?

Not by federal law. The regulation that lists where "the mandatory purchase of insurance is required" covers the A and V zones, not B, C or X. FEMA says that in these lower-risk zones, in NFIP communities, flood insurance "is available, but not mandatory, for all property owners and renters," typically at a lower rate.

You may still have to buy it:

• If your lender requires it. FloodSmart says "some banks require flood insurance even if you don't live in a high-risk area." Ask your lender about its terms.
• If the property got federal disaster aid before. Then you must have flood insurance to qualify for future disaster assistance, including FEMA grants and SBA disaster loans. FloodSmart says this requirement "is tied to a property, not an individual homeowner."

Lower risk is not no risk. FloodSmart says that from 2014 to 2024, "nearly one-third of NFIP flood insurance claims (29%) came from areas located outside of current high-risk flood areas." It also notes that "most homeowners and renters insurance don't cover flood damage." See do I need flood insurance?. [1][5][6][7]

What flood insurance costs in zones B and C now

The old label doesn't set your NFIP price. FEMA says the NFIP's current pricing approach "does not use flood zones to determine flood risk." It applied to new policies from Oct. 1, 2021, and to all renewing policies from April 1, 2022. FEMA says it looks at factors such as flood frequency, several flood types, "distance to a water source," and "property characteristics such as elevation and the cost to rebuild."

You may have heard of the Preferred Risk Policy (PRP). Los Angeles County Public Works explains that PRPs applied to structures outside the Special Flood Hazard Area with no history of flood damage claims. They ended with Risk Rating 2.0, the name of FEMA's current pricing approach. A FEMA Flood Insurance Advocate report from early 2022 describes policyholders "transitioning from a PRP to a standard policy" after "the elimination of the Preferred Risk Policy (PRP)." The county also says "PRPs are discontinued under Risk Rating 2.0."

FEMA says Community Rating System (CRS) discounts now apply to all policies in a participating community, "regardless of whether the structure is inside or outside of the Special Flood Hazard Area."

Get a quote for your own building. See flood insurance cost. [12][13][14]

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