With Microsoft Internet Explorer: in order to check the expiring date of your personal certificates through Internet Explorer, please follow the following steps: 

- Access the Tools menu, Internet Options. 

- Once there, select the Content tab. In the Certificates section Click on the Certificates button and once in the window click on the Personal tab. 

- At this point you will be shown a screen with the list of personal certificates installed in the browser. 

- Select the certificate you want to check for validity, click on View, select the details tab and select the Valid Until option. 

When using Mozilla Firefox: In order to check the expiring date of your personal certificates through Mozilla you must follow the following steps: 

- Click on the Tools/Options/Advanced button on the browser toolbar... 

- Once in this window, choose the option View Certificates and "Your Certificates". 

- Here you will be shown a list of all the certificates installed in the user profile. 

- Select the certificate you want to check for expiration and click on View. 

- At this point a box will appear displaying the "Validity" information of the certificate