For most school staff, the check needed is an enhanced DBS check with children's barred list information, because most people working in a school are in regulated activity (KCSIE 2026, paragraph 318). Staff who have regular contact with children but are not in regulated activity, such as some contractors, need an enhanced check without the barred list part (paragraph 319). Barred list information must not be requested for anyone who isn't in, or seeking, regulated activity (paragraph 320).
The applicant must show the school the original certificate before starting, or as soon as practicable afterwards (paragraph 322). If someone has to start in regulated activity before the certificate arrives, they need a separate barred list check and supervision, and in settings covered by the EYFS they can't start at all until the certificate including barred list information has arrived (paragraph 326).
The DBS Update Service lets a person keep their certificate current for a yearly fee, and lets employers make free online status checks with the person's consent (paragraphs 328 to 330). It is free for volunteers.
The DBS also decides whether to bar people. Employers have a legal duty to refer in some cases. The old name, CRB check, dates from before the DBS was set up in 2012.