Representations and Certifications Threshold

I've worked at a couple companies and my current company has acquired a couple companies since I've been with them. During my time in procurement I've seen these companies treat the requirement for Representations and Certifications differently. In reading the requirements under FAR, there does not seem to be a specific threshold where these would be required (either Micro-Purchase, Simplified Acquisition, or other). Looking at some of the required certifications though, it appears that some are actually required for ANY solicitation. Currently we have a policy setting the requirement for these at $10K which mirrors what one of the companies we acquired had. A request came internally here on whether we could raise them to $30K. Before I consider the request, I wanted to see if there is any specific regulatory or policy requirement that sets a threshold where these are required. Have any of you seen any documentation pertaining to a specific threshold? Do you currently have a threshold in your policy where these are required and has this threshold held up under DCMA Audit?