The shift from JIBOR to INDONIA addresses the need for a more transparent and transaction-based benchmark. JIBOR relied on bank estimates, while INDONIA reflects actual market rates. The reform involves related parties such as Bank Indonesia, OJK, the Ministry of Finance, and industry associations to strengthen market credibility and align with global standards. Empirical analysis demonstrates that IndONIA exhibits the highest consistency with JIBOR’s historical trends compared to both domestic and global overnight rates, making it the most statistically aligned benchmark for fallback purposes. Among the 2-, 3-, 4-, and 5-year median spreads, the 5-year option consistently shows the lowest and most stable spread values. Regression analyses further support its superiority in minimizing intercepts and enhancing convergence across different tenors. Across all tenors (1M, 3M, 6M), the 5-year median spread offers the best compromise between long-term trend stability and estimation accuracy (MAE and RMSE). This consistency confirms its robustness as the primary fallback spread adjustment paired with IndONIA. This study finds that INDONIA, when paired with a 5-year median spread adjustment, provides the most statistically stable and economically justifiable fallback for JIBOR. The evidence supports its use across multiple tenors, enhancing consistency, pricing accuracy, and risk management across financial contracts in Indonesia. To ensure a smooth transition, related authorities should coordinate to promote clarity in fallback contracts, support development of term structure instruments, and assist institutions in aligning benchmarks with risk management and reporting standards such as IFRS 17.