There are many different situations in which a LOMC might be needed or required. For example, If your home is shown in a flood zone on FEMA’s maps, you might want to confirm or challenge whether it really belongs there. Or, perhaps you’re planning a project or alteration of your structure or property, and need to know how it could affect your overall flood risk.

That’s where Letters of Map Change (LOMCs) come in. LOMCs are FEMA’s official way of correcting or updating their official floodplain maps for specific properties or projects. Some are “conditional” (meaning they’re issued before a project is built), and others are “final” (meaning they officially update FEMA’s maps).

Different types of LOMCs

You might be wondering what type of LOMC you need, or “what’s the difference between a LOMA and a LOMC?” Here, we review the various items that are all categorized as LOMC’s, in plain language:

Conditional Letter of Map Amendment (CLOMA)

Think of a CLOMA as FEMA’s “preview opinion.” It tells you whether your proposed project—if built exactly as planned—would end up outside of the high-risk flood zone. It doesn’t change the map yet, but it sets expectations for the future.

Conditional Letter of Map Revision (CLOMR)

If your proposed project could change how water flows or floods, such as altering a stream, floodway, or flood elevations, you’ll need a CLOMR. Like a CLOMA, it’s not an official map change yet, but it gives FEMA’s determination in advance.

Conditional Letter of Map Revision Based on Fill (CLOMR-F)

Planning to add fill dirt to raise land above flood levels? A CLOMR-F lets FEMA confirm in advance that your project, once completed, would likely qualify for removal from the flood zone.

Letter of Map Amendment (LOMA)

This is the one most homeowners hear about. A LOMA is FEMA’s official correction to show your home is actually above the flood zone. If your house is higher than the Base Flood Elevation, FEMA can issue a LOMA to officially remove it from the high-risk area. This can sometimes eliminate the federal flood insurance requirement.

Letter of Map Revision (LOMR)

A LOMR is a larger update to FEMA’s map. It might change flood risk zones, redraw boundaries, or adjust flood elevations. This usually applies to bigger projects or updated engineering studies—not just one property.

Letter of Map Revision Based on Fill (LOMR-F)

If fill has already been placed and your home or land is now elevated above the flood level, a LOMR-F is FEMA’s way of officially confirming that you’re no longer in the high-risk zone.

Accuracy and Support Matters

LOMCs are all about accuracy. If your property is shown in the wrong flood zone, or if you’re planning construction that changes elevations or water flow, the right type of LOMC can make sure FEMA’s map reflects reality.

For homeowners and buyers, this can mean lower insurance costs, removal of mandatory flood insurance coverage, fewer restrictions, not to mention greater protection and peace of mind.

If you believe your home doesn’t belong in a flood zone, or you’re planning a project that could impact one, knowing which LOMC to pursue can save you both wasted time and money. At MyFloodStatus, our team of Certified Floodplain Managers (CFMs) can help you understand your options and provide clarity and support moving forward.

MyFloodStatus is a flood zone determination company. We do not provide flood insurance. Please consult with a flood insurance agent to understand flood insurance premium options. The information provided is for informative purposes only and is not intended to be legal advice or a legal opinion. For legal advice, please consult an attorney.

FEMA Letter of Map Change Explained (LOMC) Types Explained