Kids have been banned from trick-or-treating this Halloween - even if they wear a mask.
A No 10 spokesman said going from door to door and interacting with neighbours is not allowed in areas under local restrictions.
Youngsters traditionally dress up as ghouls and ghosts and ask for "treats" to stop them carrying out "tricks" on their neighbours on October 31.
But Downing Street today said the rules affecting 20 million people living in lockdown across the country are "clear" and don't allow mixing between households.
The restrictions currently affect North East, North West, most of Wales, Scotland, and Northern Ireland, and part of the Midlands.
There are no exceptions for children who experts say are relatively unaffected by coronavirus.
But they won't face a fine unless they step inside someone's home - which is when a £200 penalty can apply.
And outside of lockdown areas, people will still have to stick by the rule of six, which applies nationwide.
In theory that means a person cannot answer the door to groups of trick-or-treaters bigger than five.
A No10 spokesman said: "The rules are clear on household mixing, dependent on whether you are in a local lockdown area or not.
"We are clear that everybody needs to follow the rule of six to ensure we can control and try and reduce the spread of the virus."
He added: "We are asking everybody to abide by that rule.
"The guidance is clear in terms of what we are asking the public to do."
There are new hopes coronavirus infections may be getting under control.
Daily cases in private households have dropped from an average of 9,600 last week to 8,400 this week, according to the Office for National Statistics.
The ONS said there is some "limited evidence" that the incidence rate "may be levelling off following steep increases during August and September", but uncertainty around the figures means it is too early to say.