A 16-year-old boy who became homeless after his parents abandoned him did not receive proper support from Kent County Council, a report has found.
The Local Government Ombudsman (LGO) said the boy did not accept foster care and went on to "sofa surf" but the council had not explained the benefits of being a "looked-after" child.
The council said the report did not fully reflect the case's complexity.
But it accepted the boy should have been designated a child in care.
Nigel Ellis, LGO investigations chief, said: "This vulnerable person was denied access to key welfare services that he was entitled to and that the council has a duty to provide."
The report said the boy was made homeless in 2011 after his parents left the family home without making alternative arrangements for his welfare.
'No record of explanation'
The boy did not feel able to accept foster care, it said.
But investigators found the council did not properly assess whether the boy should be looked after and there was no record of staff clearly explaining the benefits of this to him.
The LGO said the boy would have had a social worker and proper planning for adulthood and it was likely he would have had an offer of housing when he was 18, if he had been looked after.
It found the council guilty of maladministration causing injustice, recommended the authority now confirm the boy as a "leaving care child", inform the relevant housing authority and set aside £3,000 for the injustice to be used to promote his independent living.
Councillor Jenny Whittle, cabinet member for specialist children's services, said the council was committed to resolving matters and had acted on the recommendations.
She said: "We did repeatedly offer him foster care, which he refused, and gave him financial help but we accept that we failed to offer him a wider range of accommodation."
In a separate report on Tuesday, the LGO found Kent County Council had overcharged the public for home care services under a provisional charging policy between April 2011 and December 2012.
The ombudsman had investigated a complaint that the county council charged for care services before making a financial assessment, contravening government guidelines.
The council said it accepted the findings and had withdrawn the policy and agreed to refund those affected but it believed government guidance about care charging was unclear.