How long does a caution remain on a CRB check in the UK?

CRB checks were replaced by DBS checks in 2012. Once 6 years have passed (or 2 if you were under 18 at time of caution), a caution will stop showing up on a DBS check unless the offence is on the 'DBS list of offences that will never be filtered from a criminal record check' (available on the DBS website).