diff --git a/redsys/constants.py b/redsys/constants.py
index 3397aec..57981ff 100644
--- a/redsys/constants.py
+++ b/redsys/constants.py
@@ -111,3 +111,7 @@
     RECURRING_DEFERRED_PREAUTHORIZATION,
     SUCCESSIVE_RECURRING_TRANSACTION,
 ]
+
+# Payment with BIZUM
+""" Documentation: La letra "z" minúscula para el pago con BIZUM. """
+BIZUM_PAYMENT_METHOD = "z"