Next 2021 Italian Census of Population will be register-based according to the Istat Population Register (PR), which includes the list of the Italian residents. Several administrative archives such as administrative register, tax register, social security data, etc. are used to cover the population. PR hides frame imperfections as missing units, inclusion of non-population units and unrecognized duplicate listing, incorrect localization variables. Starting from PR, Istat is interested to count the living people, i,e, people that actually lives in a given place, being different from PR because of the imperfections.

Istat has planned a Population Coverage Survey (PCS) to treat the imperfections. PCS will select a municipality sample and a enumeration area sample in each municipalities. Generally, these areas will be addresses selected form the Italian Address Register. This second register could suffer from imperfections too and for some municipalities the design should select the enumeration areas defined in the 2011 Census criteria. The sampling design is planned mainly: to be efficient for counting the living people applying an optimal address sample allocation: to control the household sample size that Istat expects to be around 400,000.