Sheltered gain

My client has been told that his elderly mother is no longer capable of looking after herself and he has found a place for her in sheltered rented accommodation.

It seems highly unlikely that she will return to her home although presumably there is a slight possibility of this.

My client does not wish to sell his mother’s home and as her sole beneficiary would eventually like to move into the property himself although this would not be until he retires.

If the property is left vacant can (and should) his mother sign an election that her house should continue to be treated as her only or main residence?

And would such an election still be valid if for example it was let to students and was thus unoccupied for a month or so each summer?

Although she needs care my client’s mother’s underlying health...