The 1973 Flood Disaster Protection Act makes it mandatory that properties situated inside 'Special Flood Hazard Areas' (SFHA) must have flood insurance or else the owners will not be eligible for any kind of indirect or direct federal financial assistance. Moreover, FEMA (Federal Emergency Management Agency) uses the flood elevation certificate as a potent tool to certify building elevations of structures located inside a special flood hazard area.
The elevation certificates also helps rate post-FIRM structures and buildings. FIRMs (Flood Insurance Rate Maps) are made by FEMA and show highly flood-prone regions. These maps are used by the National Flood Insurance Program to determine proper flood insurance rates for the said region. The elevation certificate is not necessary for any the pre-FIRM structures or buildings.
Besides obligatory reasons, there can be another motive behind getting an elevation certificate issued. Your flood insurance premiums can be decreased based on the data provided by an elevation certificate. A property's elevation with respect to the base flood elevation level decides the amount of insurance premium you have to pay. So, if an elevation certificate confirms that your property's elevation is above the BFE, your insurance premiums will be significantly less.