diff --git a/README.md b/README.md
index 0985655..e4d5fa1 100644
--- a/README.md
+++ b/README.md
@@ -131,6 +131,12 @@ example: `"-JoJypAujT2z0qcWnYjW": true`
 
 example: `false`
 
+- isPremium [boolean]: has this radio channel been upgraded to premium
+This property cannot be changed by the user. After paying the premium
+fee, the Firebase functions backend will take care of switching it to `true`
+
+example: `true`
+
 - link [string]: URL describing the external homepage for a radio channel
 
 example: `"https://example.com"`
diff --git a/database.rules.json b/database.rules.json
index 601e885..285843c 100644
--- a/database.rules.json
+++ b/database.rules.json
@@ -114,6 +114,9 @@
 				"isFeatured": {
 					".validate": "newData.isBoolean() && (data.exists() && newData.val() === data.val() || newData.val() === false)"
 				},
+				"isPremium": {
+					".validate": "newData.isBoolean() && newData.val() === data.val()"
+				},
 				"link": {
 					".validate": "newData.isString() && newData.val().length < 150"
 				},