---
title: tls.client.certificate.not_before
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/variables/client-connection/tls-client-certificate-not-before
---

**Type:** TIME  
**Access:** read-only

**Available in:** recv, hash, deliver, log

A TIME of the start of the client certificate's validity period. Return value of -1 indicates error.