If you make a claim for Universal Credit and have sub-tenants or lodgers you should be aware that Universal Credit has very different rules to Housing Benefit (and out-of-work benefits).
Under Housing Benefit any sub-tenants or lodgers you have can be included as an adult occupant of your home when assessing whether you are under occupying your property (affected by the "bedroom tax") and, for private rentals, when assessing your bedroom entitlement under Local Housing Allowance. However, the income you get from sub-tenants or lodgers is included when working out your benefits (for more information see how income from sub-tenants is treated in Housing Benefit).
In contrast, under Universal Credit you will be able to keep in full all the rental income from sub-tenants or lodgers without it counted as income. However, lodgers, boarders and sub-tenants will not be counted as occupying a room in the calculation of the housing costs element of Universal Credit.
This means for social tenants the room the lodger, boarder or sub tenant occupies will still be counted as spare and you will get a spare room deduction on your Housing Element ("bedroom tax").
For private rentals when assessing your bedroom entitlement under Local Housing Allowance your lodger, boarder or sub tenant will not be counted for your room allowance.