Investment is essential for sustainable corporate growth and can be financed through debt or internally generated after-tax cash flows. This study investigates how financial risk management and tax-saving efforts interact to influence capital expenditures in Korean listed firms. Using panel data for 4,275 firm-year observations from 2017 to 2023, we employ OLS regressions with year and industry fixed effects, controlling for firm size, leverage, operating cash flow, profitability, market uncertainty, auditor quality, firm age, and foreign ownership. We find that lower effective tax rates, as a proxy for greater tax-saving efforts, are significantly associated with higher capital expenditures. Moreover, the interaction between strong financial risk management and greater tax-saving efforts magnifies investment, suggesting a synergistic effect on capital spending. Specifically, the coefficients of interactions with cash and GAAP effective tax rates are positive and statistically significant. These results highlight that aligning robust financial risk oversight with proactive tax-saving efforts strengthens investment capacity and supports sustainable growth. The findings offer managerial and policy implications regarding integrated financial–tax governance as a pathway toward long-term corporate value creation.