diff --git a/homeassistant/components/mqtt/tag.py b/homeassistant/components/mqtt/tag.py
index 848950169d8..e87a9b0da6e 100644
--- a/homeassistant/components/mqtt/tag.py
+++ b/homeassistant/components/mqtt/tag.py
@@ -8,7 +8,7 @@ import voluptuous as vol
 
 from homeassistant.components import tag
 from homeassistant.config_entries import ConfigEntry
-from homeassistant.const import CONF_DEVICE, CONF_PLATFORM, CONF_VALUE_TEMPLATE
+from homeassistant.const import CONF_DEVICE, CONF_VALUE_TEMPLATE
 from homeassistant.core import HomeAssistant
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
@@ -33,10 +33,9 @@ LOG_NAME = "Tag"
 
 TAG = "tag"
 
-PLATFORM_SCHEMA = MQTT_BASE_SCHEMA.extend(
+DISCOVERY_SCHEMA = MQTT_BASE_SCHEMA.extend(
     {
         vol.Optional(CONF_DEVICE): MQTT_ENTITY_DEVICE_INFO_SCHEMA,
-        vol.Optional(CONF_PLATFORM): "mqtt",
         vol.Required(CONF_TOPIC): valid_subscribe_topic,
         vol.Optional(CONF_VALUE_TEMPLATE): cv.template,
     },
@@ -48,7 +47,7 @@ async def async_setup_entry(hass: HomeAssistant, config_entry: ConfigEntry) -> N
     """Set up MQTT tag scanner dynamically through MQTT discovery."""
 
     setup = functools.partial(_async_setup_tag, hass, config_entry=config_entry)
-    await async_setup_entry_helper(hass, TAG, setup, PLATFORM_SCHEMA)
+    await async_setup_entry_helper(hass, TAG, setup, DISCOVERY_SCHEMA)
 
 
 async def _async_setup_tag(
@@ -121,7 +120,7 @@ class MQTTTagScanner(MqttDiscoveryDeviceUpdate):
         """Handle MQTT tag discovery updates."""
         # Update tag scanner
         try:
-            config: DiscoveryInfoType = PLATFORM_SCHEMA(discovery_data)
+            config: DiscoveryInfoType = DISCOVERY_SCHEMA(discovery_data)
         except vol.Invalid as err:
             async_handle_schema_error(discovery_data, err)
             return