The tax agency's ability to pursue taxpayers with intricate tax planning structures using evidence obtained behind closed doors has been confirmed by the Supreme Court of Appeal's following its decision to dismiss Christo Wiese and his associates' appeal in their R217 million tax dispute with the SA Revenue Service (Sars).Pieter Faber, senior tax executive at SAICA  provides analysis on how this highlights the powers of the tax agency to use evidence gathered behind closed doors to pursue taxpayers with complex tax planning structures