This study analyses the impact of a large cash transfer on intra-household bargaining as proxied by the sharing rule. The methodology for deriving bounds on the sharing rule when individual consumption data is incomplete is extended from two to m decision makers. The large cash transfer in the form of the South African Older Persons Grant is a plausibly exogenous income shock and its impact on the sharing rule bounds is analysed within a fuzzy regression discontinuity design framework. The cash transfer significantly increases the sharing rule bound by 8.4% to 8.5% for the recipient and the corresponding income elasticity of the sharing rule is between 0.15 and 0.16.