Activities on Tier 1 visa

Hi guys,

Is it illegal to sublet a room in your house to somebody else when you are on a tier 1 visa?

Why I am asking this question is that in my understanding a tier 1 visa holder is not supposed to engage in business outside employment or self-employment, and deriving a rental income may be a business that is not permitted for tier 1 holders.

Is this true? Are there any such limitations that apply to T1G dependants also?

Any thoughts?

No it's not illegal, as long as it's allowed by your tenancy agreement. However, if you are sub-letting your place you will not be able to claim this income for the purposes of Tier 1 extension or ILR as this is not your business (unless you will be sub-letting a whole lot of places). But you still need declare and pay tax on that income.