A local authority’s housing department must investigate the circumstances of a young person who makes a homeless application and ascertain if the applicant is in priority need.
As part of its enquiries into a homelessness application, the housing authority checks whether applicants have a priority need for accommodation in order to decide what duty, if any, the authority owes to the applicant. 
The authority only has a duty to provide advice and assistance in finding accommodation towards people who do not have a priority need. 
The authority owes a full housing duty, that is a duty to secure longer-term accommodation, to homeless applicants who are eligible for assistance, have a priority need, and have not became homeless intentionally. 
The authority duty to accommodate a young person with a priority need extends to family members or anyone reasonably expected to reside with the young person.
The following categories of homeless people have a priority need for accommodation: 
These have been further extended to include the following categories:
‘Relevant students’ are care leavers under the age of 25 in full-time further or higher education whose term-time accommodation is not available during vacation.
The definitions of care leavers aged 18 to 21 above include young people who have not been in care but have lived for a continuous period of minimum three months in either residential education accommodation paid for by the local education authority, or in residential rehab accommodation paid by the NHS, or have been privately fostered. 
In the case of a 16 and 17 year old, if there is any doubt as to whether they may be a ‘relevant child’ or ‘child in need’, the authority should provide interim accommodation pending clarification.
Whether homeless young people have a priority need for accommodation because they are vulnerable (in housing terms) requires an assessment. The housing authority has to decide whether a homeless young person is vulnerable as a result of one, or a combination, of the following:
Young homeless people falling outside the specific definitions above can still be vulnerable for an ‘other special reason’. This may be simply that they are a young person under the age of 25 and have no existing support networks (for example, they are estranged from their family) that could help them cope with the practicalities and costs of finding and keeping accommodation. 
When assessing if young homeless applicants are vulnerable, the housing authority should consider whether, when homeless, they would be significantly more vulnerable than an ordinarily person in need of accommodation and likely to suffer greater harm in the same situation. This could Vulnerability in this context is a homeless applicant’s vulnerability if s/he is not provided with accommodation, not her/his need of care and support generally. The vulnerability assessment is a composite decision that involves not only the issue of whether an applicant can find and keep accommodation, but also whether s/he is less able to manage with being homeless so that s/he would suffer injury or detriment in circumstances where a less vulnerable person would not. All the particular difficulties of the applicant should be carefully considered together. it is not crucial how the local authority words its decision letters, provided that it can show that it has carried out the required composite assessment by addressing the correct questions and carefully considering all the relevant circumstances of the applicant. 
If the housing authority decides that a homeless young person is eligible for assistance and in priority need it must provide interim accommodation from the date of the homelessness application until it has completed its enquiries. 
Once it has finished its enquiries, it no longer has to find longer-term accommodation for the young person if it is satisfied that they are also not intentionally homeless and that they have a local connection.
The housing authority can still offer accommodation to those not in priority need, but is not obliged to
 s.184 Housing Act 1996.
 s.192 Housing Act 1996.
 s.193 Housing Act 1996.
 R (on the application of Ogbeni) v Tower Hamlets  EWHC (Admin).
 see s.189 Housing Act 1996.
 see Homelessness (Priority Need for Accommodation) (England) Order 2002.
 see para 10.40 Homelessness Code of Guidance for Local Authorities, DCLG, July 2006.
 see paras 10.12-10.35 Homelessness Code of Guidance for Local Authorities, DCLG, July 2006.
 para 10.33 Homelessness Code of Guidance for Local Authorities, DCLG, July 2006.
 Hotak v Southwark LBC : Kanu v Southwark LBC : Johnson v Solihull MBC  UKSC 30.
 s.188 Housing Act 1996.