Since 2022, CBS has applied the widely accepted ETHOS classification. Only the description was changed and not the study population or methodology.

ETHOS stands for ‘European Typology of Homelessness and Housing Exclusion’, where homelessness is classed as the lack of proper housing. ETHOS Light was developed as a tool to estimate the number of homeless people and is considered the minimum classification of homelessness. The classification includes the following groups:

1. people living in public spaces;
2. people in emergency shelters;
3. people in temporary shelters for homeless people;
4. people exiting institutions;
5. people living in non-standard locations (such as in a car, squat or holiday home);
6. people temporarily staying with family, friends or acquaintances.

This classification is also used in the surveys conducted by the Hogeschool Utrecht University of Applied Sciences in the Netherlands and by the University of Leuven in Belgium. They add a further group to the original categories: those facing imminent eviction from their home. These people are included because eviction is a known route to homelessness.

This CBS survey focuses on the population of homeless people aged 18 to 64. These are people who sleep outdoors, in indoor public spaces such as the lobbies of buildings, bicycle parking areas, train and bus stations, shopping malls or in cars, or indoors at community shelters or temporary emergency shelters, and people staying temporarily with friends, acquaintances or relatives on a non-structural basis and who have no fixed place to live.

Homeless people aged 18-64 years oldMensen die leven in de openbare ruimte (groene categorie) In an emergency shelter (groene categorie) Staying temporarily with family, friends, acquaintances (groene categorie) Living in non-conventional locations (e.g. car, squat, holiday home) (groene categorie) In a temporary shelter for homeless people (oranje categorie) Exiting an institution (rode categorie) At risk of eviction (rode categorie) In this study, CBS looks at the groups shown in green. The orange category is taken partly into consideration. The red categories fall outside the CBS study. At risk ofeviction Living innon-conventionallocations(e.g. car,squat,holiday home) Exiting aninstitution In a temporaryshelter forhomeless people In anemergency shelter Livingoutdoors In this study, CBS looks at the groups shown in green. The orange category is taken partly into consideration. The red categories fall outside the CBS study. Homeless people aged 18-64 years Staying temporarily with family, friends, acquaintances

When this delineation is compared to the ETHOS Light classification, CBS focuses on categories 1, 2, 5 and 6. Category 3 is only covered by CBS’s estimate in the case of people staying in crisis shelters or alternative temporary shelters. People who are in social care structurally (on a 24-hour basis), such as in social boarding houses, women's shelters or assisted living, are not included in the estimate. The CBS survey does not look at people exiting institutions (category 4) or those facing imminent eviction.

The CBS survey also excludes people who cannot appear in the registers; this is a prerequisite for applying the method of estimation. This includes asylum seekers who have exhausted all legal options, people who are in the Netherlands illegally, those below the age of 18 years and those over the age of 65. The first two categories are not included in the Personal Records Database. Younger and older homeless people cannot, in principle, be included in the register for welfare benefits for people without a fixed address.

No distinction can be made between the ETHOS Light categories in the results.