This paper investigates the economic incentive of German onshore wind turbines to curtail generation during negative wholesale electricity prices by reconstructing the applicable regulatory framework for the installed wind fleet. Negative electricity prices are becoming increasingly relevant in power systems with high shares of variable renewable generation. Whether wind power operators have an economic incentive to curtail generation during such periods depends strongly on the applicable remuneration and market participation regime. Based on turbine-level data from the German Federal Network Agency and the commissioning date of each turbine, the operational onshore wind capacity is classified into three remuneration groups: post-support turbines, turbines with voluntary direct marketing, and turbines subject to mandatory direct marketing. The resulting curtailment thresholds are derived from the interaction between wholesale electricity prices, reference remuneration values, and monthly wind market values. By the end of 2025, the analyzed German onshore wind fleet comprises approximately 67.7 GW of net installed capacity, of which 12.49 GW are classified as post-support capacity, 22.45 GW as capacity with voluntary direct marketing, and 32.77 GW as capacity subject to mandatory direct marketing. The analysis shows that the economic response to negative prices differs substantially across these regulatory groups. Using monthly wind market values for 2026, most of the capacity has a direct incentive to curtail once wholesale prices become negative, whereas in periods with lower market values, market premiums can shift the curtailment threshold to significantly more negative price levels. The results demonstrate that regulatory remuneration schemes are a key determinant of the price responsiveness of the German onshore wind fleet and should therefore be explicitly considered when assessing the effects of negative electricity prices on renewable generation.