The act provided for the establishment of a constantly-maintained national register of the civilian population of the United Kingdom and the Isle of Man, and for the issuance of identity cards based on data held in the register, and required civilians to present their identity cards on demand to police officers and other authorised persons.

On the following Sunday and Monday the enumerators visited every householder, checked the form and then issued a completed identity card for each of the residents.

[1] The last person prosecuted under the Act was Harry Willcock, who had refused to produce his identity card for a police officer in December 1950.

[citation needed] Unlike the decennial censuses, the 1939 register was designed as a working document for the duration of the war, and it was later used in the foundation of the National Health Service.

Those born after 1939 are recorded separately and that register has not been released)  – discuss] as well as subsequent changes of name, notably in the case of single women who married after 1939.

[6][13] The original register books relating to England and Wales were collated and maintained by the Central National Registration Office at Southport, Merseyside, and are now held by the Health and Social Care Information Centre (NHS Digital).

[3][7] In 2010, the NHS began offering to conduct searches of the registers compiled on 29 September 1939 to members of the public upon payment of a fee, and would provide extracts of the information found so long as it was known that it only concerned people who were no longer living.

[14] In 2015, The National Archives entered into an agreement under which the original 29 September 1939 registers—as updated by the NHS until 1991—have been scanned, digitised, and made available subject to privacy restrictions on the subscription-based Findmypast website.

However, on the grounds that a Scottish census record is invariably sealed for 100 years, the information in the extract is limited to the person's address, age, occupation, and marital status at the time of registration.

[3] Following two successful applications under the Freedom of Information Act 2000 in 2010, PRONI in principle allows members of the public to submit a request in the form of a general research enquiry to obtain an extract from the 1939 register for a specified address, including information about inhabitants born over 100 years ago and/or residents whose proof of death is submitted with the request.