Article 21 outlines the conditions under which a Registrant must apply to the Authority for tax deregistration. This is required if the Registrant ceases making Taxable Supplies, or if the value of their Taxable Supplies over 12 consecutive months falls below the Voluntary Registration Threshold, provided they do not meet the condition in Clause 2 of Article 17. The article also grants the Authority discretionary power to deregister a person, based on controls in the Executive Regulation, if their continued registration could prejudice the tax system's integrity. Importantly, tax deregistration does not waive the Authority’s right to claim any due tax or administrative penalties.