Prime Minister Boris Johnson is working on coronavirus certification which would get you into events, travel, theatre and gigs later this summer.
Widely described as vaccine passports, they could also indicate if you'd been tested for Covid-19 recently, or had natural immunity from previous infection, reports the Mirror.
And it could help Brits get back to some semblance of normality as other restrictions are eased over the summer.
But they've prompted a revolt from some Conservative MPs, after ministers claimed "we aim to remove all legal limits on social contact and restore our freedoms" from June 21.
Labour MPs also have concerns on civil liberties grounds, and fears about how the system will actually work.
There is no start date for a Covid passport, no final design, and a promise that you won't need it to go to a pub when beer gardens open in England on Monday.
So what is the debate actually about and what might passports look like?
Here's everything you need to know.
What is a Covid passport?
A vaccine passport is a term for a system where people can provide they are Covid 'safe' to get into a venue, to travel, or in a work setting.
The government describes it as 'Covid certification', because it won't just mean showing you've been vaccinated.
It could also show if you have natural immunity or if you'd had a recent negative coronavirus test.
The government doesn't like the term 'vaccine passport' because it says it over-simplifies the purpose of the certification. But it is generally used by other people and has entered common use.
How would it work?
The NHS is working on providing both "digital and non-digital" ways for you to show your vaccine, testing or antibody status in a Covid 'certificate' or 'passport'.
It's understood this may use a re-worked version of the NHS Covid-19 app, which has already been downloaded more than 22 million times for testing and venue check-ins.
The tool could show one or all of three things to 'certify' your Covid status:
- Your up-to-date vaccine record;
- Whether you've had a negative lateral flow (rapid) or PCR (lab-based) test, taken on the same day or the day before your admission to a venue;
- Proof of natural immunity, such as through a previous positive PCR test no less than 180 days ago, as long as you've completed the self-isolation period.
Why are they being developed?
For foreign travel it's because countries will demand a vaccine status to allow entry to Brits.
But for domestic reasons within the UK it becomes more complicated. Ministers had claimed domestic passport were discriminatory and would not happen, but have since U-turned.
Explaining the massive change of heart, the government said it had to act because pubs and other venues would start asking for people's Covid status regardless.
"Even without government intervention, Covid-status certification is likely to become a feature of our lives until the threat from the pandemic recedes," the government says.
"Likewise, in the UK, businesses and other organisations are able to ask customers for proof of Covid-status in order to access their premises, as long as they are compliant with equalities legislation.
"The government believes that introducing a ban on this would in most cases be an unjustified intrusion on how businesses choose to make their premises safe."
Where will you probably need a Covid passport?
The government says certification is most likely at ticketed events, such as:
- Theatres
- Nightclubs
- Mass events such as festivals or sports events
That's because "large numbers of people are brought together in close proximity."
Where might you need a Covid passport?
The government has not ruled out introducing Covid passports - or allowing them to be used by individual businesses - in pubs, restaurants, cafes and bars.
The review says certification "could play a role in reducing social distancing requirements in other settings which people tend to visit more frequently, for example in hospitality settings."
This could mean, for example, that you have to show a Covid passport at your local pub in exchange for the rule of six being dropped indoors from June 21.
But the government has ruled out any chance of passports being needed in hospitality venues before June 21.
You will not have to show a Covid passport when beer gardens reopen in England on April 12, or when indoor areas of pubs reopen from May 17.
The review adds: "The government recognises this has significant implications for businesses and their customers. So this will be further considered in consultation with industry."
Where will you definitely not need a Covid passport?
There are some settings where the government says Covid passports "should never be required".
This is "in order to ensure access for all".
They include:
- Essential public services
- Public transport
- Essential shops
When will the passports be introduced?
There is no exact date as yet - but there are a few clues.
Firstly, we know passports won't be trialled through the Events Research Programme - which is piloting new ways of safely bringing crowds back for big events.
The programme starts in 10 days' time with a comedy gig in Liverpool and runs to May 15 - when the FA Cup Final takes place at Wembley Stadium.
Secondly, we know further proposals are to be presented to Parliament later this month.
Thirdly, big events such as gigs and sports fixtures can only resume from May 17 at the earlier anyway - so passports aren't needed until then.
Fourthly, the government has specifically guaranteed passports won't be needed in hospitality venues (pubs and restaurants) before June 21.
So it seems that any passport scheme is months away.
What about people with medical exemptions?
It's not clear what will happen yet.
The government is still working out the moral and ethical ramifications of passports to ensure people are not discriminated against if they are unable to get the vaccine.
There are also questions over whether vaccine passports will be required for children - who generally aren't being vaccinated.
The government says: "It is important that there are appropriate exemptions for people for whom vaccination is not advised and repeated testing is difficult.
"Equally, the government wants to be sure that the benefits of any such approach are fully integrated in public debate and that the deliverability of Covid-status certification is rigorously tested, along with analysis of the potential economic impacts that Covid-status certification would have across different settings."
Could Covid passports be defeated in Parliament?
Potentially, they could.
The use of certificates is opposed by at least 40 Conservative MPs and Labour is also sceptical.
This could be enough opposition to wipe out Boris Johnson's Parliamentary majority, although it seems likely a compromise would be struck.
Vaccines Minister Nadhim Zahawi said there will be a vote on a scheme. He said Michael Gove is consulting with stakeholders, including Parliamentarians adding "so we are not there yet".
He said the PM has made it very clear if we do get to that place "then of course we will go to Parliament for a vote."
