Knockout questions cover requirements that are genuinely non-negotiable, such as holding a valid driving licence for a delivery role, being able to work the advertised shifts or having a required professional registration. They are usually asked at the point of application, with the hiring team agreeing in advance which answers mean a candidate cannot go further. Keeping the list short makes the application quicker to complete.
Used well, knockout questions save time for both sides, because candidates learn early that a role does not suit their circumstances. Used badly, they exclude capable people over requirements that are preferences rather than needs, and some, such as rigid availability rules, can affect certain groups more than others. Each question should be tied to the job, worded clearly and checked periodically for adverse impact.