diff --git a/README.md b/README.md
index 54d3a63..9a790d4 100644
--- a/README.md
+++ b/README.md
@@ -26,6 +26,7 @@ Kubernetes is an open‑source platform that automates the deployment, scaling,
   - [Manifest - StringData](#manifest---stringdata)
   - [Inline with heredoc and environment variables](#inline-with-heredoc-and-environment-variables)
   - [substr](#substr)
+  - [get certificate end date](#get-certificate-end-date)
 - [service accounts](#service-accounts)
 - [core-dns](#core-dns)
 
@@ -356,6 +357,12 @@ envsubst < ./secret.yaml | kubectl apply -f -
 
 ```
 
+### get certificate end date
+
+``` bash
+kubectl get secret certificate-name-tls -o "jsonpath={.data['tls\.crt']}" | base64 --decode | openssl x509 -enddate -noout
+```
+
 ## service accounts
 
 **Get service account token:**