If you're like my client who couldn't remember what her TIN number is, there's a very simple way to learn the essential nine digit number. Call up the BIR Contact Center at 981.8888 . Please be reminded that this action that I'm describing in this post is only applicable for individuals with an existing TIN number. For other circumstances, please visit the BIR website . After the automated voice welcome message, the first option is immediately TIN verification and registration inquiry. Press 1 and you will be forwarded to a BIR Contact Center agent.