An adult person who normally lives in your house, who is not your partner may be a non-dependant. Non-dependants are expected to contribute towards your rent and/or Council Tax, or towards your mortgage and service charges if you are an owner-occupier.
If you have other people living with you, and you are claiming Housing Benefit or the Universal Credit Housing Element to help you pay your rent, or Council Tax Support to help you pay your Council Tax, your entitlement may be reduced by a non-dependant deduction.
If you are an owner-occupier your support for mortgage interest will be reduced by a non-dependant deduction.
Examples of non-dependants:
Grown-up children who no-one receives child benefit for
Relatives or family friends staying with you without a formal tenancy agreement
People who are not non-dependants:
Children you receive Child Benefit for
Lodger, boarder or tenant who pays you rent
Anyone who is jointly liable for the rent, mortgage or Council Tax
Your live-in landlord