Anyone travelling overseas from England from Monday will have to prove they are allowed to travel, or risk being turned away from the airport and fined.
They will need to complete a "Declaration to Travel" document from a government website.
The form sets out that their trip is permitted under current restrictions, such as for education or work.
Police officers will be conducting spot checks and may ask travellers to produce a completed form.
It will be an offence to fail to produce a completed form and individuals could face a £200 fine, the Department for Transport warned.
The form must be downloaded from the government's website, signed before travel and carried or downloaded on to a mobile phone.
The three-page form requires travellers to fill out their personal details and tick a box indicating why they are leaving the country.
Airlines will check the forms have been completed before boarding, either at check-in (online or check-in desk) or at the departure gate.
Passengers who do not have a valid form may be denied access to their flight.
Airlines are legally obliged to set out on their website that the form must be completed before travelling.
Current lockdown restrictions mean it is illegal to travel abroad without a permitted reason, such as for work, volunteering, education, medical grounds or funerals.
Foreign holidays for people in England will not be permitted before 17 May under Boris Johnson's roadmap for easing coronavirus lockdown restrictions.
Passengers who are identified by police as attempting to travel internationally for reasons that are not currently permitted will be asked to return home and risk being fined for breaking the rules.
The fines start at £200 and soar to a maximum of £6,400.
What about travelling from Northern Ireland, Scotland or Wales?
There are slightly different restrictions in Northern Ireland, Scotland and Wales but, as yet, no declaration for travel form is required.
Under current UK-wide Covid-19 restrictions, you must not travel, including abroad, unless you have a legally permitted reason to do so.
It is illegal to travel abroad from anywhere in the UK for holidays and other leisure purposes.
Travellers arriving anywhere in the UK now have to take two coronavirus tests while quarantining, while some must pay to self-isolate at a hotel.