This article studies the existence and magnitude of financial investment constraints in Germany between 2006 and 2012 with a special emphasis on small and medium‐sized firms. The core contention is that the sensitivity of the investment rate to the cash flow rate is a function of a firm's financial position contributing to its access to external finance. The application of a nonlinear panel threshold model reveals that the marginal effect of the cash flow rate on the investment rate is almost twice as strong for ‘high debt’ firms compared to ‘low debt’ firms. This result holds for six out of seven balance sheet threshold variables. For a single specification, the results reveal a non‐monotonic relationship between the cash flow rate and investment rate. Firm size, however, does not explain differences in the cash‐flow‐investment nexus.