How much rent to charge a sibling.

Ratmouse

They're not exactly forthcoming with information,  I haven't pushed for fear of "rocking the boat" before everything is done with regards to the transfer of equity.(this took around 3.5 months) 
In my opinion it's reasonable to have the expectation they have been making some effort.
To find something by now. There's no way I can  wait another  9 months. 

Seems like I may need to ask them to find a rental. 

Flatfacedcat

don't be so tight rent free

If your sibling tends to exploit you then charge the average market price, a fair amount, not more not less. If your sibling doesn't tend to exploit you, then don't charge anything at all and let her/him stay at your place totally for free as much as she/he needs. This is just what I would do, your answer is within yourself - to find it out is enough to put yourself in the position of your sibling and ask yourself in what way you would like to be treated if your sibling was in your place

FlorayG

Legally, now he is a lodger and you can just give him notice to quit; however there are more moral issues here because of you buying him out ( presumably while you were both living there) so you need to consider things you possibly haven't said here; however, he's got the money for selling the house to you and now is still living there seems like he has the best end of the deal. I would charge the going rate for 'rooms to rent' in your area, which you can find out on Spare Room website