diff --git a/.changeset/fair-keys-see.md b/.changeset/fair-keys-see.md
new file mode 100644
index 0000000000..d987f75d4e
--- /dev/null
+++ b/.changeset/fair-keys-see.md
@@ -0,0 +1,5 @@
+---
+"@effect-app/vue-components": patch
+---
+
+Enhances default extraction with extended classes and tagged union components in OmegaForm
diff --git a/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnion.vue b/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnion.vue
index 489f8e1e19..8418c90d6c 100644
--- a/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnion.vue
+++ b/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnion.vue
@@ -23,20 +23,27 @@ defineProps<{
 </script>
 
 <template>
-  <slot name="OmegaCustomInput">
-    <form.Input
-      :name="(name ? `${name}._tag` : '_tag') as FieldPath<From>"
-      :label="label"
-      :type="type ?? 'select'"
-      :options="options"
-    />
-  </slot>
-  <form.Field :name="(name ?? '') as any">
-    <template #default="{ field, state }">
-      <slot v-if="state.value" />
+  <form.Field :name="(name ? `${name}._tag` : '_tag') as any">
+    <template #default="inputProps">
+      <slot
+        name="OmegaCustomInput"
+        v-bind="inputProps"
+      >
+        <form.Input
+          :name="(name ? `${name}._tag` : '_tag') as FieldPath<From>"
+          :label="label"
+          :type="type ?? 'select'"
+          :options="options"
+        />
+      </slot>
+      <slot />
+      <slot
+        v-if="inputProps.state.value"
+        name="OmegaCommon"
+      />
       <OmegaTaggedUnionInternal
-        :field="field as any"
-        :state="state.value"
+        :field="inputProps.field as any"
+        :state="inputProps.state.value"
         :name="name"
       >
         <template
diff --git a/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnionInternal.vue b/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnionInternal.vue
index 73ba19ed9d..d12feb9b39 100644
--- a/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnionInternal.vue
+++ b/packages/vue-components/src/components/OmegaForm/OmegaTaggedUnionInternal.vue
@@ -1,7 +1,7 @@
 <template>
   <slot
-    v-if="state?._tag"
-    :name="`${name ? `${name}.` : ''}${state?._tag}`"
+    v-if="state"
+    :name="`${name ? `${name}.` : ''}${state}`"
     v-bind="{ field, state }"
   />
 </template>
@@ -26,7 +26,7 @@ const props = defineProps<{
 }>()
 
 // Watch for _tag changes
-watch(() => props.state?._tag, (newTag, oldTag) => {
+watch(() => props.state, (newTag, oldTag) => {
   if (newTag === null) {
     props.field.setValue(null as DeepValue<From, Name>)
   }
diff --git a/packages/vue-components/src/components/OmegaForm/useOmegaForm.ts b/packages/vue-components/src/components/OmegaForm/useOmegaForm.ts
index b2b18bccf4..e5a5d272e0 100644
--- a/packages/vue-components/src/components/OmegaForm/useOmegaForm.ts
+++ b/packages/vue-components/src/components/OmegaForm/useOmegaForm.ts
@@ -791,11 +791,27 @@ export const useOmegaForm = <
   const extractDefaultsFromAST = (schemaObj: any): any => {
     const result: Record<string, any> = {}
 
-    // Check if this schema is a union
-    if (schemaObj?.members && Array.isArray(schemaObj.members)) {
+    // If this schema has a .make() method (like ExtendedClass), use it to get complete defaults
+    // This is more reliable than manually extracting fields, especially for classes
+    if (typeof schemaObj?.make === "function") {
+      try {
+        const instance = schemaObj.make({})
+        // For ExtendedClass, the instance is already in the correct encoded format
+        return instance
+      } catch {
+        // If make() fails, fall through to manual extraction
+      }
+    }
+
+    // Check if this schema is a union - check both direct property and AST
+    const unionMembers = schemaObj?.members
+      || (schemaObj?.ast?._tag === "Union" && schemaObj.ast.types
+        ? schemaObj.ast.types.map((t: any) => S.make(t))
+        : null)
+    if (unionMembers && Array.isArray(unionMembers)) {
       // For unions, we try to find the first member that has a complete set of defaults
       // Priority is given to members with default values for discriminator fields
-      for (const member of schemaObj.members) {
+      for (const member of unionMembers) {
         const memberDefaults = extractDefaultsFromAST(member)
         if (Object.keys(memberDefaults).length > 0) {
           // Check if this member has a default value for a discriminator field (like _tag)