Implications of DS living in our (empty) rental property until sale - council tax, change of address etc?

[Quandry]

Just trying to think this through and wonder if it's
a) possible
b) advisable
and what the implications might be - legal, financial etc

Would appreciate throughts/ experience...

Our family has an ex-rental property (bought with money from an inheritance) and jointly owned by me and my two adult sons (aged 25 and 22). It's been rented out for 10 years but is now empty, redecorated, and up for sale. No interest/ offers yet.
DS1 lives elsewhere and is happy for it to be sold. It's in the next town from us, so I manage it/ visit etc.

DS2 has just left uni and has asked if he can live in it until it's sold. DS1 and I are fine with this in principle, but suggested DS2 should transfer Council Tax and bills into his name. This would actually reduce the council tax paid as he would get single person discount and there would be no empty property premium applied if the house is still unsold next April.

HOWEVER DS2 is about to start a post-grad course elsewhere which means he wouldn't be there all the time - just back some weekends and Christmas/ Easter for a month each time, then from July next year. He will claim student exemption on his term time rental.

Could he still consider this to be his 'main residence'?

It may vary by local authority but in mine he could not claim a single person discount on one property and a student discount on the other. The one with the student discount would be classed as his main residence, and the other would be classed as a second home which has higher council tax.

Yes, that's what I wondered about - guess he'll have to check.

The other thing is that because the house could be sold at any point he doesn't want to change all his address on legal documents (drivers licence, bank statements etc - they're currently still registered at our home address) but I wondered if that might lead to problems down the line with credit searches/ identity checks etc?

if you want your home to sell quickly, don’t have a young man living in there. Sorry, but unless it’s very unusual, it’ll just put people off and lower the price.

Also you won't be able to claim any costs against your rental income nor capital gains for the period he's living in it, such as utilities, repairs, mortgage interest etc. Had it been left empty, some of your costs would have been set against income/gains.