The Proactive Health Office (ARPA-H) seeks solutions to improve American healthspan and outcomes through population-level wellness, novel early-detection methods, and system-level innovations for proactive health delivery. Amendment 3 is effective immediately, with prior submissions evaluated under their original solicitation terms. Key updates include revisions to administrative requirements for conflicts of interest, research security, intellectual property, and human/animal subjects. The cost proposal documents were updated with clarified labor rate definitions and an increased unit cost threshold for supporting documentation from $5,000 to $10,000. Solution summaries and proposals must be submitted via the provided ARPA-H web portals.