diff --git a/schema/definitions/0.8.0/schema/fmu_results.json b/schema/definitions/0.8.0/schema/fmu_results.json
index 6f19eead7..2836bdc83 100644
--- a/schema/definitions/0.8.0/schema/fmu_results.json
+++ b/schema/definitions/0.8.0/schema/fmu_results.json
@@ -30,6 +30,7 @@
     "fmu.iteration.uuid",
     "fmu.model",
     "fmu.realization.id",
+    "fmu.realization.is_reference",
     "fmu.realization.name",
     "fmu.realization.uuid",
     "fmu.workflow",
@@ -6140,6 +6141,18 @@
           "title": "Id",
           "type": "integer"
         },
+        "is_reference": {
+          "anyOf": [
+            {
+              "type": "boolean"
+            },
+            {
+              "type": "null"
+            }
+          ],
+          "default": null,
+          "title": "Is Reference"
+        },
         "jobs": {
           "anyOf": [
             {},
diff --git a/src/fmu/dataio/_model/fields.py b/src/fmu/dataio/_model/fields.py
index f09bbc125..3996135ad 100644
--- a/src/fmu/dataio/_model/fields.py
+++ b/src/fmu/dataio/_model/fields.py
@@ -298,6 +298,21 @@ class Realization(BaseModel):
     """The universally unique identifier for this realization. It is a hash of
     ``fmu.case.uuid`` and ``fmu.iteration.uuid`` and ``fmu.realization.id``."""
 
+    is_reference: Optional[bool] = Field(default=None)
+    """
+    Flag used to determine if this realization is tagged as a reference.
+
+    Typically, a reference realization is one that includes prediction surfaces and
+    maintains all other input parameters at their default settings. However, caution
+    must be exercised when putting logic upon this field, as this is simply a selected
+    realization by the user and no guarantees of what the realization represents
+    can be made.
+
+    .. note::
+        Please note that users shall not set this flag in the metadata upon export;
+        it is intended to be configured through interactions with the Sumo GUI.
+    """
+
 
 class CountryItem(BaseModel):
     """A single country in the ``smda.masterdata.country`` list of countries
diff --git a/src/fmu/dataio/_model/root.py b/src/fmu/dataio/_model/root.py
index a5b1cc44d..56d74c526 100644
--- a/src/fmu/dataio/_model/root.py
+++ b/src/fmu/dataio/_model/root.py
@@ -278,6 +278,7 @@ def dump() -> dict:
                     "fmu.iteration.uuid",
                     "fmu.model",
                     "fmu.realization.id",
+                    "fmu.realization.is_reference",
                     "fmu.realization.name",
                     "fmu.realization.uuid",
                     "fmu.workflow",