diff --git a/BuildingSync.xsd b/BuildingSync.xsd
index 3bbcdded..e3e577e9 100644
--- a/BuildingSync.xsd
+++ b/BuildingSync.xsd
@@ -618,6 +618,11 @@
       <xs:element ref="auc:OwnershipStatus" minOccurs="0"/>
       <xs:element ref="auc:PrimaryContactID" minOccurs="0"/>
       <xs:element ref="auc:TenantIDs" minOccurs="0" maxOccurs="unbounded"/>
+      <xs:element name="MultiTenant" type="xs:boolean" minOccurs="0">
+        <xs:annotation>
+          <xs:documentation>True if the building is a multi-tenant building.</xs:documentation>
+        </xs:annotation>
+      </xs:element>
       <xs:element name="NAICSCode" type="xs:string" minOccurs="0">
         <xs:annotation>
           <xs:documentation>North American Industry Classification System (NAICS) code.</xs:documentation>
diff --git a/proposals/2021/Add MultiTenant.md b/proposals/2021/Add MultiTenant.md
new file mode 100644
index 00000000..b7132d9b
--- /dev/null
+++ b/proposals/2021/Add MultiTenant.md	
@@ -0,0 +1,54 @@
+# Add MultiTenant to Building
+
+## Overview
+
+This proposal is to add the `MultiTenant` element as a child element of `Building` element, with boolean options.  
+
+## Justification
+
+True if the building is a multi-tenant building.
+
+## UDFs
+
+Currently this is conveyed in Audit Template via:
+`/auc:BuildingSync/auc:Facilities/auc:Facility/auc:Sites/auc:Site/auc:Buildings/auc:Building/auc:UserDefinedFields/auc:UserDefinedField[auc:FieldName/text() = Multi Tenant]/auc:FieldValue`.
+Our proposal is to add it under a `Building`.
+
+## Example
+
+```xml
+    <auc:Facilities>
+        <auc:Facility ID="F1">
+            <auc:Buildings>
+                <auc:Building ID="B1">
+                    <auc:MultiTenant>True</auc:MultiTenant>
+                </auc:Building>
+            </auc:Buildings>
+        </auc:Facility>
+    </auc:Facilities>
+```
+
+## Implementation
+
+```xml
+      <xs:element name="Buildings" minOccurs="0">
+        <xs:complexType>
+          <xs:sequence>
+            <xs:element name="Building" type="auc:BuildingType" maxOccurs="unbounded">
+              <xs:annotation>
+                <xs:documentation>A building is a single structure wholly or partially enclosed within exterior walls, or within exterior and abutment walls (party walls), and a roof, affording shelter to persons, animals, or property. A building can be two or more units held in the condominium form of ownership that are governed by the same board of managers.</xs:documentation>
+              </xs:annotation>
+            </xs:element>
+          </xs:sequence>
+        </xs:complexType>
+      </xs:element>
+      ...
+      <xs:element name="MultiTenant" type="xs:boolean" minOccurs="0">
+        <xs:annotation>
+          <xs:documentation>True if the building is a multi-tenant building.</xs:documentation>
+        </xs:annotation>
+      </xs:element>
+      ...
+```
+
+## References
\ No newline at end of file