Mandatory HMO licensing is the legal obligation to seek an HMO license before certain kinds of property can be rented out in England i.e. large HMOs.
Mandatory HMO licensing can be contrasted with additional licensing and selective licensing, whereby whether a property needs a license depends on the individual council local council.
Please note that since 1 October 2018 all large HMOs fall under the mandatory HMO licensing scheme, regardless of how many storeys it has.