The RDL covers almost all the income declarations of households in Metropolitan France.

To elaborate the Localised Disposable Income (RDL), INSEE has the following two files (sent each year by the Tax General Directorate - DGI): the income declaration file (n°2042) and the local residence tax ratepayer file (dwellings taxed as main or second homes, other premises taxed separately such as car parks, garages, etc).

Each year (N), INSEE uses these files to process the data:
- relating to the income declarations of year N (sent by taxpayers in April N+1). Tax households are listed, identified by means of an identifier;
- on the persons linked to a dwelling subject to local residence tax and used as a main home: they are identified by both an occupied-dwelling identifier and a tax-household identifier (identical to that in the income declaration file).

This allows the switch from the notion of tax household to that of tax dwelling: all the tax households attached to the same dwelling are grouped together under the same dwelling identifier (that of the local residence tax payer) to form the tax dwelling.

For better accuracy of the RDL source, adjustment methods are used.
A first adjustment to the population census data results in better representativeness of the local-level data (region).
A second, national-level adjustment is then made to ensure the consistency of distribution of living standards between the Social Income and Tax Revenue Survey (ERFS) which refers to the national level and the Localised Disposable Income system (RDL).

For each year, these adjustments provide a median living standard (and thus a poverty rate) which is more or less identical from one source to the next, bearing in mind the differences of scope.