A Multi-Scale Monetary Precision Framework for Distributed Banking Systems

Abstract

Modern banking systems simultaneously maintain monetary values across computation (8-10 decimal places), ledger posting ($\mathbf{4}-\mathbf{8}$decimal places), and customer presentation (2 decimal places) scales. In distributed microservice and event-driven architectures, unmanaged transitions between these scales introduce rounding drift, ledger divergence, reconciliation breaks, and non-deterministic replay risks that threaten audit compliance and regulatory reporting accuracy. This paper investigates how distributed banking systems can manage multi-scale monetary precision while preserving deterministic balances and auditability. The proposed Multi-Scale Monetary Precision Model (MSMP) defines three scale classes, three explicit precision boundaries, and four correctness invariants governing deterministic posting, ledger conservation, presentation consistency, and fractional carry forward. A taxonomy of three canonical failure modes, namely early rounding, boundary truncation, and nondeterministic aggregation, is presented together with four architectural patterns designed to ensure precision-safe monetary propagation. Evaluation on a synthetic bankingrealistic workload (106accounts over 365 days) demonstrates that MSMP reduces cumulative monetary drift by up to 99.9 %, eliminates reconciliation breaks entirely, and achieves 100 % replay determinism, with computational overhead of approximately 18 %. These results establish monetary precision governance as a first-class architectural control for audit-ready distributed financial systems.