This document details the significant impact of the Principal Purpose Test (PPT) on Private Equity (PE), Venture Capital (VC) investments, and Mergers & Acquisitions (M&A) deals. It explains how PPT, introduced by the Multilateral Instrument (MLI), prevents tax treaty abuse by requiring genuine commercial substance over mere tax benefits. The guide covers the implications for PE/VC investments, M&A transactions, and offers practical mitigation strategies, including robust documentation and substance-driven approaches. It's an essential read for investors and businesses involved in cross-border transactions seeking to ensure compliance and safeguard treaty benefits.