All BLS numbers come from the household survey and the business survey. They apply the responses to the population as a whole and calculate the percentages. When the number of people on unemployment benefits are mentioned, that is a separate data set and the BLS does not use that. The number of people who have stopped looking for work comes from the BLS survey. When someone falls of the unemployment rolls they no longer follow them, unless theory household just happens to be one of the survey households.