diff --git a/asyncapi-core/src/test/kotlin/com/asyncapi/v3/_0_0/model/TagTest.kt b/asyncapi-core/src/test/kotlin/com/asyncapi/v3/_0_0/model/TagTest.kt
new file mode 100644
index 00000000..e18a3ca9
--- /dev/null
+++ b/asyncapi-core/src/test/kotlin/com/asyncapi/v3/_0_0/model/TagTest.kt
@@ -0,0 +1,50 @@
+package com.asyncapi.v3._0_0.model
+
+import com.asyncapi.v3.Reference
+import com.asyncapi.v3.SerDeTest
+
+/**
+ * @author Pavel Bodiachevskii
+ */
+class TagTestWithReferenceToExternalDocs: SerDeTest<Tag>() {
+
+    override fun objectClass() = Tag::class.java
+
+    override fun baseObjectJson() = "/json/v3/3.0.0/model/tag with reference to externalDocs.json"
+
+    override fun extendedObjectJson() = "/json/v3/3.0.0/model/tag with reference to externalDocs - extended.json"
+
+    override fun wronglyExtendedObjectJson() = "/json/v3/3.0.0/model/tag with reference to externalDocs - wrongly extended.json"
+
+    override fun build(): Tag {
+        return Tag(
+                "user",
+                "User-related messages",
+                Reference("#/components/external-doc")
+        )
+    }
+
+}
+
+/**
+ * @author Pavel Bodiachevskii
+ */
+class TagTest: SerDeTest<Tag>() {
+
+    override fun objectClass() = Tag::class.java
+
+    override fun baseObjectJson() = "/json/v3/3.0.0/model/tag.json"
+
+    override fun extendedObjectJson() = "/json/v3/3.0.0/model/tag - extended.json"
+
+    override fun wronglyExtendedObjectJson() = "/json/v3/3.0.0/model/tag - wrongly extended.json"
+
+    override fun build(): Tag {
+        return Tag(
+                "user",
+                "User-related messages",
+                ExternalDocumentationTest().build()
+        )
+    }
+
+}
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - extended.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - extended.json
new file mode 100644
index 00000000..d41b395e
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - extended.json	
@@ -0,0 +1,13 @@
+{
+  "name" : "user",
+  "description" : "User-related messages",
+  "externalDocs" : {
+    "description" : "Find more info here",
+    "url" : "https://example.com"
+  },
+  "x-number" : 0,
+  "x-string" : "",
+  "x-object" : {
+    "property" : { }
+  }
+}
\ No newline at end of file
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - wrongly extended.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - wrongly extended.json
new file mode 100644
index 00000000..7a65e27e
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag - wrongly extended.json	
@@ -0,0 +1,14 @@
+{
+  "name": "user",
+  "description": "User-related messages",
+  "externalDocs": {
+    "description" : "Find more info here",
+    "url" : "https://example.com"
+  },
+  "x-number": 0,
+  "x-string": "",
+  "x-object": {
+    "property": {}
+  },
+  "ext-number": 1
+}
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - extended.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - extended.json
new file mode 100644
index 00000000..1d10e2f8
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - extended.json	
@@ -0,0 +1,12 @@
+{
+  "name" : "user",
+  "description" : "User-related messages",
+  "externalDocs" : {
+    "$ref" : "#/components/external-doc"
+  },
+  "x-number" : 0,
+  "x-string" : "",
+  "x-object" : {
+    "property" : { }
+  }
+}
\ No newline at end of file
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - wrongly extended.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - wrongly extended.json
new file mode 100644
index 00000000..79e4f263
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs - wrongly extended.json	
@@ -0,0 +1,13 @@
+{
+  "name": "user",
+  "description": "User-related messages",
+  "externalDocs": {
+    "$ref": "#/components/external-doc"
+  },
+  "x-number": 0,
+  "x-string": "",
+  "x-object": {
+    "property": {}
+  },
+  "ext-number": 1
+}
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs.json
new file mode 100644
index 00000000..f9ad85f8
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag with reference to externalDocs.json	
@@ -0,0 +1,7 @@
+{
+  "name": "user",
+  "description": "User-related messages",
+  "externalDocs": {
+    "$ref": "#/components/external-doc"
+  }
+}
diff --git a/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag.json b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag.json
new file mode 100644
index 00000000..aa06e030
--- /dev/null
+++ b/asyncapi-core/src/test/resources/json/v3/3.0.0/model/tag.json
@@ -0,0 +1,8 @@
+{
+  "name": "user",
+  "description": "User-related messages",
+  "externalDocs": {
+    "description" : "Find more info here",
+    "url" : "https://example.com"
+  }
+}