Here is everything you need to know:
What are the new rules?
From Tuesday (September 22) all parts of Bradford, Kirklees, Calderdale, will now be banned from socialising with other people outside of their own households or support bubble in private homes and gardens.
Why is it happening?
Ministers announced a tightening of rules in response to “major increases” in cases, with Merseyside, Warrington, Halton and Lancashire – excluding Blackpool and Greater Manchester – escalated to “areas of intervention”.
But case numbers in parts of West Yorkshire are still high too, so that is why some areas are included in the new measures.
Aren't parts of West Yorkshire already under restrictions?
Yes, large parts of Kirklees, Bradford and Calderdale had restrictions relaxed at the end of last month - but some areas have remained under local lockdown measures.
Bradford city and Keighley in Bradford, Halifax in Calderdale and Dewsbury and Batley in Kirklees have all remained under restrictions.
But from Tuesday, separate households will be banned from meeting each other at home or in private gardens across the whole of Bradford, Kirklees, Calderdale.
When are new restrictions introduced in an area?
There is no set level of infection that triggers this in a particular place, but if it posts more than 40 coronavirus cases per 100,000 people, it is likely that extra restrictions will be considered.
But the number of infections is not the only factor considered.
The rate per 100,000 in Leeds has been hovering around 70 for several days - but the city has not yet faced any extra measures.
How long will the restrictions last?
The situations are regularly reviewed and when the number of infections falls, restrictions start to be eased again.
Can police enforce the rules?
According to the BBC: "Police have powers to make sure people stick to the restrictions. For example, if they believe that somebody is staying away overnight, they can tell them to return home.
"They can also fine people for breaking the rules, and may issue a "prohibition notice" directing somebody not to do something.
"But if a resident from a locked-down area wants to go to a bar in another part of the city, for example, there is nothing legally to stop them.
"Instead, the government hopes people's sense of civic responsibility will see them follow guidance to stay at home."
Are any other restrictions in place?
Yes, the 'rule of six' - which forbids social gatherings of more than six people anywhere (inside and outside) in England - still applies.