diff --git a/app/SubBooking.php b/app/SubBooking.php
index ee87c88..693cb76 100644
--- a/app/SubBooking.php
+++ b/app/SubBooking.php
@@ -6,6 +6,11 @@ use Illuminate\Database\Eloquent\Model;
 
 class SubBooking extends Model
 {
+    public function signedAmount()
+    {
+        return $this->ioType->factor * $this->amount;
+    }
+
     /**************************************************************************
      * BOOKINGS                                                               *
      **************************************************************************/