BBC today
English travellers face fines and losing flights without new permit.
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.