Mortgages. If you are buying with a mortgage or converting an existing property that you own into an HMO, you need to ensure your lender is happy that the property will be used as an HMO.
Planning, as per point 4, Plymouth has implemented an Article 4 Direction. Planning permission is required when changing from a C3 class single dwelling to a C4 class which is an HMO up to 6 people. An HMO occupied by more than six people will be in class use Sui Generis.
InInsurance, you will need to inform your insurance company that the property is an HMO. Expect a slightly higher premium as the insurance company will class an HMO as more risk than a standard residential let.
HMO Standards, each local authority will have a set of standards that they expect and require. Plymouth City Council publishes its rules in a guide. A copy of the latest Plymouth HMO Standards can be found at:
https://www.plymouth.gov.uk/sites/default/files/HMO_Standards_Nov_2018.pdf