The 2021 Census questionnaire ensured continuation with previous censuses that were carried out in Malta and conformed to the UNECE and Eurostat recommendations on concepts and definitions for population censuses.  The 2021 Census permitted people, for the first time, to fill-in the census questionnaire through an online form which was accessible to the public from October 2021. Nearly 230,000 dwellings received an official letter with the login credentials via post in September 2021.

In a step towards a fully digitalised census, enumerators visiting dwellings recorded the information on tablet computers, rather than traditional paper questionnaires. Data collection by means of telephone was also possible. An application available on the tablet devices allowed the enumerators to identify any dwellings which did not submit the questionnaire online so that they could assist them in the process or fill out the form on their behalf. The synchronisation of multiple systems occurred overnight to ensure a smooth running of the process. Data collection from the field or by telephone was carried out between 8 and 28 November 2021. The enumeration process in certain areas was also extended to 15 December 2021.

Nearly 1,000 enumerators were recruited for canvassing and fieldwork activities within their designated area (formally referred to as enumeration areas) consisting of several streets or parts thereof in a locality, typically encompassing an average of 200 dwellings. The delineation of enumeration areas was carried out by means of optimisation algorithms developed internally and the use of Geographical Information Systems (GIS).

To ensure a high-coverage rate of the preliminary Census results, the Census Office made extensive use of several administrative registers to estimate the information which was not yet available at the time of the writing of the preliminary report which was issued in August 2022.