This study focuses on the payment process of a tissue paper manufacturing plant in Cambodia, which is overseen by its headquarters in Thailand. The identified issues include delays in payment processing and high costs associated with international document delivery. The objectives of this study were to 1) reduce payment processing time and 2) minimize international delivery costs. Tools such as the Fishbone Diagram and Pareto Chart were used to analyze the factors causing delays. The methodology involved documenting the work steps in a flow process chart, measuring activity durations, and identifying inefficiencies. To address these issues, the ECRS technique (Eliminate, Combine, Rearrange, and Simplify) was applied, and an Internet banking system was introduced to replace the need for international document delivery. The results demonstrate significant improvements. The number of steps in the payment process was reduced from 38 to 23, a decrease of 39.47%. Payment processing time dropped from 137.20 hours (17.15 days) to 57.83 hours (7.23 days). Additionally, international document delivery costs were eliminated, resulting in 100% savings. This research underscores the effectiveness of process optimization techniques and internet banking solutions in reducing operational inefficiencies and costs savings of 79,886.99 Baht per year