Knockouts are for genuine hard requirements, the conditions under which a hire is impossible, such as work authorization, a required license, or a language minimum. They are not a ranking tool. Applicants who fail an unreviewed knockout drop to a Role Match of zero, so use them only where a no is truly a no.
The catalog
You pick from a catalog of compliant knockout types, including skill present or verified, language minimum or certified, minimum relevant years, education level or field, location, work authorization, visa sponsorship, relocation, travel, schedule compatibility, license and certification checks, background check willingness, and custom yes or no and numeric questions.
Some screening bases are deliberately absent, including age, salary history, family or marital status, disability before offer, national origin, religion, criminal history before the offer stage, and credit history. These create legal exposure in many jurisdictions, so the builder does not offer them at all.
Guardrails you will notice
For standard types the applicant-facing question text is auto-generated and read-only. This protects you from accidentally rewording a lawful check into an unlawful question. Custom questions are screened for eight risk categories, and a high-severity match requires an explicit acknowledgment that you have consulted legal counsel before you can save.
Timing and the simulation
Most knockouts run at apply time. Skill knockouts defer to after the simulation when your attached simulation tests that same skill, so the work sample, not the claim, settles the question. The builder warns you when a knockout-required skill is not tested by your simulation.
When an applicant fails a knockout after the simulation
The application is flagged with the requirement that was not met, and you choose. Reject with honest feedback, override the knockout and advance them, or leave them in the pipeline while you verify the requirement directly. The applicant sees an honest explanation either way, never silence.