For incumbents to be accountable for their issue stances, voters must sanction incumbents whose positions are “out of step” with their own. We test the electoral accountability of British legislators for their stance on Brexit. We find that there is very limited issue accountability. Individuals who disagreed with their representative’s stance on Brexit were 3 percentage points less likely to vote for them. The aggregate consequences of these individual effects are limited. A one-standard-deviation increase in the proportion of constituents agreeing with their incumbent’s Brexit stance is associated with an increase of 0.53 percentage points in incumbent vote share. These effects are one and a half times larger when the main challenger has a different Brexit stance to the incumbent. A follow-up survey of Members of Parliament (MPs) shows that MPs’ estimates of the effects of congruence are similar in magnitude. Our findings suggest that issue accountability is conditional in nature and limited in magnitude even for an issue such as Brexit, which should be maximally amenable to such effects.