In complex SoC designs, intellectual property (IP) blocks are critical yet vulnerable. Unintended modifications to IP during placement, routing or fill stages often go undetected by traditional DRC, leading to functional failures, performance degradation and costly re-spins. This paper introduces Calibre IP Checker, an automated, shift-left solution designed to guarantee IP integrity. It works by precisely comparing placed IP instances against their original versions, flagging all modifications, whether to IP blocks, standard cells or even text labels. By enabling early detection and resolution of these issues, Calibre IP Checker ensures correct IP functionality, performance and manufacturability, significantly reducing design iterations and accelerating time to tape-out.