This study examines the financial requirements of delivering Senior High School (SHS) education under the K to 12 Basic Education Program at the International Philippine School in Al-Khobar (IPSA). With strands in Accountancy, Business, and Management (ABM); Science, Technology, Engineering, and Mathematics (STEM); Humanities and Social Sciences (HUMSS); and Arts and Design (AD), the research aimed to determine the actual cost per strand and assess the school’s financial sustainability. An Activity-Based Costing (ABC) framework was applied to IPSA’s SHS operations for School Year 2021–2022. Data were gathered from enrollment records, payroll, departmental expenses, and administrative reports. Costs were allocated to activity pools such as registration, training and education, school activities, clinic, library, and administrative support. Average cost per student per strand was computed and compared with traditional costing and current school fees. Findings revealed a total SHS departmental expenditure of SR 1,384,636.71, averaging SR 8,600.23 per student annually. Training and education accounted for 70.57% of costs, while administrative support comprised 18.15%. Strand-specific costs varied: AD had the highest average cost per student (SR 13,645.29), followed by HUMSS (SR 11,681.58), ABM (SR 9,593.41), and STEM (SR 7,736.41). Comparisons with traditional costing showed significant variances, particularly in AD (89.91%) and HUMSS (62.58%). Fee analysis indicated that STEM generated a surplus, while ABM, HUMSS, and AD operated at deficits. The study demonstrates that ABC provides a more accurate reflection of strand-specific educational costs compared to traditional costing. Results highlight the need for IPSA to realign tuition and miscellaneous fees with actual expenditures, optimize resource allocation, and strengthen financial sustainability. Institutionalizing ABC as a continuous monitoring tool is recommended to guide budgeting, cost control, and strategic planning.

Keywords: Activity-Based Costing, Senior High School Education, cost calculation, financial sustainability, K to 12 Program, educational management, Al-Khobar, KSA