People are being asked to work from home from today, unless it's absolutely necessary to attend in person.
It's one of several new restrictions that have now come into effect, as the Government works to slow the spread of COVID-19 amid a fresh surge in infection.
The return to full work from home comes despite a relaxation of the remote working rules in September, when employers were able to start a 'phased and cautious' return to the workplace.
The Government's being warned the measure may not have the desired effect on COVID-19 case numbers.
Neil McDonnell, Chief Executive of ISME, claims the economy could be damaged for little benefit.
He said: "There is a degree of frustration on our part... that the epidemiological data that was out at the start of November, giving details of transmission, does not suggest the workplace is a significant vector for transmission.
"The danger is we could shut down offices without actually substantially improving the caseload."
He suggested it will have a "knock-on effect throughout the economy", with reduced footfall in towns and cities impacting the likes of cafés, restaurants and retails.
Under the new rules, bars, restaurants and nightclubs will also now have to shut from midnight.
COVID-19 certs will also be mandatory for all cinemas and theatres - a rule that had previously only applied for venues that had increased capacity.
Weddings will also have to wrap up by midnight, as hotel bars are included in the new closing times.