DARPA's Information Innovation Office has issued a Request for Information (RFI) titled “Provably Private and Performant Payment Paradigms” (P5). The RFI, DARPA-PS-26-23, seeks information on designing international payment systems with a strong focus on privacy, efficiency, and security to enhance the resilience and competitiveness of American financial institutions globally. The deadline for responses is February 13, 2026. DARPA is interested in understanding the current state of the art and identifying technical innovations for achieving provably private and performant international payment systems. The RFI specifically asks for definitions of payment system privacy, potential tradeoffs between financial privacy, transaction volume, marginal cost, and payment security, appropriate privacy and security threat models, and differences in security and privacy challenges between payment systems and general computer networking contexts. The agency aims to identify relevant technological capabilities and may issue a follow-up Broad Agency Announcement or Program Solicitation.