Some employees want the freedom to work longer hours – to earn more overtime for example.  In the UK, workers over 18 can opt out of the 48 hour restriction.  To do this they must formally declare in writing that they wish to opt out.  This opt out agreement can subsequently be cancelled by the employee at any time by giving at least 7 days written notice, or the notice period that is set out in their opt out agreement which may be up to three months.