diff --git a/app/Person.php b/app/Person.php
index 2a8e8b2..344b720 100644
--- a/app/Person.php
+++ b/app/Person.php
@@ -127,6 +127,22 @@ class Person extends Model
         return $this->hasManyThrough('\App\SubBooking', '\App\PersonTarget');
     }
 
+    /*
+     * Return, if the person is even.
+     *
+     * @return boolean
+     */
+    public function isEven()
+    {
+        foreach ($this->targets as $target) {
+            if (!$target->isPaid()) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /*
      * Get the full name of the person.
      *
@@ -140,4 +156,7 @@ class Person extends Model
             return $this->surname . ' ' . $this->name_or_company;
         }
     }
+
+    // Make all attributes mass assignable.
+    protected $guarded = [];
 }