have a residential mortgage on house and we need to find the flat ( downsizing) close to work. can we ask the bank to let us to rent our house on a residential property and then buy the flat with residential mortgage. we have put 25% deposit on the house and have had it 2.5 years. I spoke to bank they said ok but I need to get assured short tenancy agreement with the tenant. can this agreement be signed with just one person? do I then have to declare rent + claim expenses I put for repairing the property on my self assessment form?