Boris Johnson has said the new coronavirus tiers have "a sunset" clause - or expiry date - of 3 February, as he tries to fight off a backlash from Tory MPs.
The prime minister has angered some of his party with a plan to impose stringent restrictions across much of England when the national lockdown ends on Wednesday.
In a letter to colleagues ahead of a Commons vote on the restrictions on Tuesday, Mr Johnson insisted the tiered measures for local areas will be reviewed every fortnight.
"Regulations have a sunset of 3 February," he writes.
"After the fourth fortnightly review (27 January), parliament will have another vote on the tiered approach, determining whether the measures stay in place until the end of March."
Mr Johnson said the first review on 16 December would consider the views of local directors of public health, with a final decision on whether any areas should change tiers made at a cabinet committee.
The changes would then come into effect on 19 December.
In a further olive branch to MPs, the PM committed to publish more data and outline what circumstances need to change for an area to move down a tier, as well analysis of the health, economic and social impacts of the measures taken to suppress coronavirus.
Writing in the Mail on Sunday, Mr Johnson warned there will be "disastrous consequences" for the NHS without the introduction of new tiered coronavirus restrictions.
He wrote: "We are so nearly out of our captivity. We can see the sunlit upland pastures ahead. But if we try to jump the fence now, we will simply tangle ourselves in the last barbed wire, with disastrous consequences for the NHS.
"So let's do the job properly. Let's work together, and with tiering, testing and vaccines let's make 2021 the year we kick COVID out, take back control of our lives and reclaim all the things we love."
Foreign Secretary Dominic Raab, appearing on Sky News' Sophy Ridge on Sunday show, said the new tiered restrictions were necessary to "bear down" on COVID-19.
"The reality is that we want to come out of national lockdown and stay out of it," he said.
"We are starting with a more restrictive approach than previously with the localised approach, but that allows us to ease up when we are confident the virus is going down and stabilised - there's a review every two weeks."
In another broadcast interview, Mr Raab told the BBC's Andrew Marr Show there was a "risk" of a third wave of coronavirus infections "if we don't get the balance right".
And he refused to rule out a third national lockdown in England if there was another spike in cases in the New Year.
"We're doing everything we can to avoid that," he said.
According to a tally by Sky News, more than 60 Tory MPs have voiced their unhappiness over tiering or have said they are unlikely to support the measures when it comes to the vote.
Some 99% of England's population will fall under the two toughest tiers when the second national lockdown ends.
About 32 million people - covering 57.3% of England - will fall into Tier 2, and 23.3 million people - 41.5% of the population - are going to be placed in Tier 3.
Only the Isle of Wight, Cornwall, and the Isles of Scilly will be under the lightest Tier 1 controls, while large swathes of the Midlands, North East and North West are in the most restrictive Tier 3.
Several Tories have said they will vote against the new tiers next week, including 1922 Committee chairman Sir Graham Brady, Bournemouth East MP Tobias Ellwood and Poole MP Sir Robert Syms.
Steve Baker, deputy chairman of the COVID Recovery Group which has been critical of lockdown restrictions, said the "authoritarianism at work today is truly appalling".
"The government must publish its analysis of the impact interventions are likely to have on controlling COVID, as well as the non-COVID health impact and the impact on society, people's livelihoods and businesses," he said.
Sir Roger Gale, MP for the Kent constituency of North Thanet, criticised the decision to place all of the county in Tier 3, telling Sky News he fears people will "skip over the boundary" to go to a nearby pub in Tier 2.
But Chris Hopson, chief executive of NHS Providers, urged MPs to think what the NHS might be like in January, saying: "You need to take the precautions now to ensure that the NHS doesn't get overwhelmed at what is always its busiest time of year."
Another 479 coronavirus deaths in the UK were announced on Saturday, taking the total to 58,030.
- SKY NEWS