How much are high-income taxpayers willing to forgo to shelter one dollar of their income from taxes? Exploring a natural experiment and using administrative individual tax data, we estimate the marginal cost of income-sheltering behaviors and the elasticity of taxable income for high-income individuals. Our estimates from static and dynamic bunching models show that the marginal cost of sheltering one dollar from a 5 percent marginal income tax is about 2 cents. The estimated cost is heterogeneous by employment type, sex, and age.