Fines of £800 for people caught at house parties will become law at 5pm on Friday.
The latest coronavirus laws are coming into force as part of tougher measures to crack down on illegal gatherings during the pandemic.
The penalty will apply for groups of more than 15 people and will double after each offence, up to a maximum of £6,400 for repeat offenders, Home Secretary Priti Patel said last week when she announced the plans.
This supersedes current rules where the fines stand at £200.
But the £10,000 penalties for unlawful groups of more than 30 people will still only apply to the organiser.
According to the legislation, which has now been published and is called the Health Protection (Coronavirus, Restrictions) (All Tiers and Self-Isolation) (England) (Amendment) Regulations 2021, the £800 fine is cut to £400 if paid within 14 days.
As well as those in private dwellings, the rule also applies to similar gatherings in "educational accommodation", the documents setting out the new law said.