Incomplete take-up persists in means-tested programs, even when benefits are allocated automatically. This paper examines why eligible households do not use the energy voucher in France, which is sent directly to beneficiaries. The results show that the determinants of non-take-up differ across the income distribution through two effects. Among modest-income households, non-use is driven by a size effect. Take-up increases sharply when the voucher represents a larger share of household income, with a probability of use by up to 94 percentage points. Among the poorest households, non-use reflects a learning effect linked to administrative familiarity. Households who received the voucher the previous year are about 25 percentage points more likely to use it. Overall, take-up follows a non-linear pattern across income levels, reflecting the joint effect of administrative constraints and the relative value of the benefit.