Reach me if you can: How to boost participation of rich households in wealth surveys?

Wealth surveys systematically under-represent affluent households because wealthy respondents are less likely to participate. We study whether targeted incentives can improve top-tail coverage in the Slovak Household Finance and Consumption Survey (HFCS). Using census data, we pre-identify affluent households and randomly assign them to treatment and control groups. Treated households are offered a limited-edition non-cash participation incentive: a proof-quality silver collector coin. The incentive increases participation by 11–14 percentage points, equivalent to a roughly 40% increase relative to the participation rate among non-incentivized wealthy households, with the largest effects occurring when combined with personal interviewer contact. The treatment disproportionately attracts financially sophisticated households, improving coverage of the upper tail of the wealth distribution without reducing response quality. Incorporating these additional households increases measured mean wealth, raises the wealth Gini coefficient by up to 6.5%, and improves alignment between survey aggregates and National Accounts. Our findings show that fieldwork design and participation incentives materially affect the measurement of wealth inequality and may contribute to cross-country differences in HFCS-based statistics.