RT Journal Article A1 Baharuddin Baharuddin A1 Budi Krisnanto A1 Abdul Gafar Samalam A1 Muhammad Rizal T1 The capital buffer paradox: Strong heterogeneity in profitability determinants between small and over capitalized banks in Indonesia JF Priviet Social Sciences Journal YR 2025 VO 5 IS 12 SP 600-620 DO 10.55942/pssj.v5i12.1053 AB The Indonesian banking sector faces a paradox of maintaining high capital buffers for stability while pursuing profitability amid digital disruption. This study examines the profitability determinants of conventional commercial banks, with a novel focus on testing the moderating role of the Capital Adequacy Ratio (CAR) in the loan-to-deposit ratio (LDR) and return on assets (ROA) relationship a mechanism hypothesized to explain previous empirical inconsistencies. Using quarterly panel data from 43 banks from Q1 2020 to Q3 2025 (989 observations) and a Fixed Effects model corrected with robust standard errors, the results reveal three key findings. First, the moderation hypothesis is rejected; high capital buffers do not significantly alter the impact of LDR on ROA. Second, operational efficiency (BOPO) proves to be the most consistent and dominant determinant of profitability. Most importantly, the key contribution lies in the discovery of sharp heterogeneity: traditional determinant models exhibit very strong explanatory power (R² = 66%) for small banks (CAR ≤ 25.1%) but fail to explain profitability for large, over capitalized banks (R² = 26.1%), where no traditional variables are significant. This demonstrates that profitability drivers evolve with bank scale, rendering one size fits all policy and strategic approaches ineffective. Consequently, regulators must implement differentiated macroprudential policies, while bank management should tailor core strategies based on their specific segment. K1 bank profitability, return on assets, capital adequacy ratio, loan to deposit ratio, moderation, over capitalization, Indonesian banking LK https://journal.privietlab.org/index.php/PSSJ/article/view/1053 ER