Why do you need my tax number? 02 October 2018 08:28 Updated It is a legal requirement for banking services to hold your tax identification number (TIN). This is part of the Know Your Customer (KYC) procedure to help enforce Anti-Money Laundering (AML) and Counter Terrorist Financing (CTF) policies. Related articles What is a TIN? What is KYC? What are the main features of the Bitwala account? Is my national identity document accepted by IDnow?