People in England who refuse an order to self-isolate could be fined up to £10,000 from 28 September.
The new legal duty requires people to self-isolate if they test positive for coronavirus, or are traced as a close contact.
New measures also include a one-off £500 support payment for those on lower incomes, and a penalty for employers who punish those told to self-isolate.
Fines will initially start at £1,000 rising to £10,000 for repeat offenders, and for “the most egregious breaches”.
Until now, advice to self-isolate has been guidance only.
The UK government hopes the new fines will be replicated in Wales, Scotland and Northern Ireland – which all have powers to set their own coronavirus rules.
More than 19,000 fines have been issued in England and Wales for alleged breaches of coronavirus laws, the attorney general said earlier this week, but more than half have not been paid so far.
“Follow Rules To Avoid Lockdown”
Britain’s Secretary of Health, Matt Hancock warned of coronavirus restrictions getting tougher as the government introduces £10,000 fines for people who fail to self-isolate.
Asked if England could face another national lockdown, Mr Hancock said: “I don’t rule it out, I don’t want to see it.”
“If everybody follows the rules then we can avoid further national lockdown,” he warned.
The prime minister is understood to be considering a ban on households mixing, and reducing opening hours for pubs.
However, M Boris Johnson could take the form of a two-week mini lockdown in England in an aim to stem a recent surge in cases.
On Saturday, a further 4,422 new Covid-19 cases and 27 deaths were reported in the UK.