Neighbours are being encouraged by the Government to report Covid sufferers who are not self-isolating to the police, on the day it becomes an offence punishable with a fine of up to £10,000.
Police will also conduct spot checks in areas with high infection rates and in high-risk groups.
The news comes amid concerns that people are becoming increasingly fatigued by lockdown measures and suggestions by Boris Johnson that the virus is spreading because people are not abiding by the rules.
Watch: How does the Covid-19 tracing app work?
Like other coronavirus restrictions, it has not been subject to a vote in Parliament, and the Prime Minister has been warned that he faces "certain" defeat in Parliament this week if he refuses demands to give MPs more of a say.
Up to 100 Tory MPs are now said to be ready to back a proposed amendment to the Coronavirus Act, tabled by Sir Graham Brady, chairman of the 1922 committee of Tory backbenchers, which would force ministers to give Parliament a vote on future measures.
They believe the Government will back down if the Speaker selects the amendment for a vote, and party whips are said to have abandoned any attempt to bring the rebels into line.
Matt Hancock, the Health Secretary, wrote to all Tory MPs on Sunday explaining why the Coronavirus Act in its current form was needed, only to be accused of "missing the mark" by rebels who said the Government would be in a stronger position if future Covid measures had the backing of Parliament.
The Government made it clear on Sunday night that it would act on tip-offs from third parties who have "identified others who have tested positive, but are not self-isolating". Whitehall sources confirmed that police would be expected to investigate calls made to its 101 non-emergency number.
Among the steps that will be taken to make sure that people are complying with the rules, the Government also cites "using police resources to check compliance in highest incidence areas and in high-risk groups, based on local intelligence" and "NHS test and trace call handlers increasing contact with those self-isolating".
Earlier this month, the Prime Minister was at odds with his own ministers after he said he was not a fan of "sneak culture". That was after Priti Patel, the Home Secretary, said she would report her neighbours if she saw them breaking the "rule of six".
On Sunday, Ms Patel put people on notice that police will crack down hard on those who are reported for not self-isolating, saying: "These new fines are a clear sign that we will not allow those who break the rules to reverse the hard-won progress made by the law-abiding majority."
Her comments, and the Government's insistence that it will act on public tip-offs, will be seen as a warning to police forces that they must enforce the new law, following rows with police chiefs who had indicated a reluctance to dedicate resources to crackdowns.
That came after Mr Johnson said the Army could be brought in to help with the response, in what police chiefs saw as a direct challenge to their authority.
People who fail to self-isolate can expect to be fined £1,000, rising to £10,000 for repeat offenders.
Last week, a joint survey by King's College London, University College London and Public Health England found that just one in 10 people contacted by NHS test and trace had stayed at home for the required 14 days.
Watch: What is meant by its 'basic reproduction number'?
Mr Johnson laid the blame for the current increase in infection rates at the door of the public, saying it was "very difficult to ask the British population uniformly to obey guidelines in the way that is necessary".
If someone receives a positive test result, they are now required by law to self-isolate for 10 days after displaying symptoms or after the date of the test, if they did not have symptoms. Other members of their household must self-isolate for 14 days. People who are contacted by NHS test and trace and told to self-isolate are legally obliged to do so.
Mr Hancock warned that if infections continued to rise "we will not hesitate to put in place further measures".
Tighter restrictions including a ban on households mixing indoors and the two-week closure of bars and restaurants could be imposed in the worst-hit areas as early as this week, it was claimed on Sunday night.