People who continue to flout coronavirus lockdown rules will be breaking the law and could be arrested by police.
Those who ignore tougher restrictions on movement could be hit with a £60 fine initially and another for £120 for a second offence, the Home Office warned.
Officers will have the power to enforce rules on staying at home and avoiding non-essential travel from Thursday.
They can order members of the public to go home, leave an area and have the power to disperse a group.
Police can also take steps to make sure parents are stopping their children from breaking the rules.
According to the guidance, the cost of initial fixed penalty notices will be cut to £30 if paid within 14 days and those who do not pay could be taken to court and risk facing costs for unlimited fines.
The Home Office said: “If an individual continues to refuse to comply, they will be acting unlawfully, and the police may arrest them where deemed proportionate and necessary.
“However, in the first instance, the police will always apply their common sense and discretion.”
Home Secretary Priti Patel said: “The Prime Minister has been clear on what we need to do: stay at home to protect our NHS and save lives.
“All our frontline services really are the best of us and are doing an incredible job to stop this terrible virus from spreading.
“That’s why I’m giving the police these new enforcement powers, to protect the public and keep people safe.”