Defined the overarching data structure for the accounts and transactions

src/App.vue

@@ -11,6 +11,27 @@ export default {
   name: 'app',
   components: {
     Header
+  },
+  data: function() {
+    return {
+      accounts: [
+        {
+          "AccountName": "", 
+          "Bank": "", 
+          "Transactions": [
+            {
+              "Date": "",
+              "TransactionTypeDescription": "",
+              "Description": "",
+              "OutgoingPayment": true,
+              "Amount": 0,
+              "Balance": 0, 
+              "Tags": []
+            }
+          ]
+        }
+      ]
+    }
   }
 }
 </script>