diff --git a/conf/plugins/eap-radius.opt b/conf/plugins/eap-radius.opt
index 2a6786dd9..7d511155b 100644
--- a/conf/plugins/eap-radius.opt
+++ b/conf/plugins/eap-radius.opt
@@ -11,7 +11,7 @@ charon.plugins.eap-radius.accounting_interval = 0
 
 charon.plugins.eap-radius.accounting_requires_vip = no
 	If enabled, accounting is disabled unless an IKE_SA has at least one
-	virtual IP.
+	virtual IP. Only for IKEv2, for IKEv1 a virtual IP is strictly necessary.
 
 charon.plugins.eap-radius.class_group = no
 	Use class attributes in Access-Accept messages as group membership
diff --git a/src/libcharon/plugins/eap_radius/eap_radius_accounting.c b/src/libcharon/plugins/eap_radius/eap_radius_accounting.c
index cef19305c..7a76fdd07 100644
--- a/src/libcharon/plugins/eap_radius/eap_radius_accounting.c
+++ b/src/libcharon/plugins/eap_radius/eap_radius_accounting.c
@@ -860,11 +860,6 @@ METHOD(listener_t, message_hook, bool,
 	if (plain && ike_sa->get_state(ike_sa) == IKE_ESTABLISHED &&
 		!incoming && !message->get_request(message))
 	{
-		if (ike_sa->get_version(ike_sa) == IKEV1 &&
-			message->get_exchange_type(message) == TRANSACTION)
-		{
-			send_start(this, ike_sa);
-		}
 		if (ike_sa->get_version(ike_sa) == IKEV2 &&
 			message->get_exchange_type(message) == IKE_AUTH)
 		{
@@ -874,6 +869,17 @@ METHOD(listener_t, message_hook, bool,
 	return TRUE;
 }
 
+METHOD(listener_t, assign_vips, bool,
+	private_eap_radius_accounting_t *this, ike_sa_t *ike_sa, bool assign)
+{
+	/* start accounting as soon as the virtual IP is set */
+	if (assign && ike_sa->get_version(ike_sa) == IKEV1)
+	{
+		send_start(this, ike_sa);
+	}
+	return TRUE;
+}
+
 METHOD(listener_t, ike_rekey, bool,
 	private_eap_radius_accounting_t *this, ike_sa_t *old, ike_sa_t *new)
 {
@@ -1003,6 +1009,7 @@ eap_radius_accounting_t *eap_radius_accounting_create()
 				.ike_updown = _ike_updown,
 				.ike_rekey = _ike_rekey,
 				.message = _message_hook,
+				.assign_vips = _assign_vips,
 				.child_updown = _child_updown,
 				.child_rekey = _child_rekey,
 				.children_migrate = _children_migrate,