Letting agents are urging landlords to be aware of changes to planning and licensing laws for rental properties.
Around 30 councils in England have indicated they will enforce planning rule called ‘Article 4’ which means landlords will need planning permission if a home is let as house in multiple occupation (HMO) to more than two tenants sharing kitchens and bathrooms.
In council areas not enforcing Article 4, HMO licenses only apply to homes with six or more unrelated tenants living in one property with shared amenities such as a bathroom and kitchen over three levels.
Many of the councils want Article 4 rules as a tool to stop the spread of student houses.
Problems over noise, parking, litter and general poor behaviour by students have triggered protests from neighbours and councillors see the rule as a way of controlling complaints.
Landlords need to take care that they do not commit to buying a property as an HMO in an area subject to planning controls before permission is granted in writing.
Existing shared houses are not subject to Article 4 rules.
Ian Potter, of the Association of residential Letting Agents (ARLA), said: "HMO licensing and planning applications are not a new issue for landlords, but now there is the added complication of Article 4. There is no room for complacency - failure to comply could result in a hefty fine.
"It is therefore important for any landlord considering changing the use of a property to fully research the regulations in their area. For landlords with portfolios spanning more than one local authority area, this may mean different rules apply for each property. Factoring in the possible additional costs of purchasing the licence is also vital."
HMO licences cost on average £400-£600.
Oxford already operates Article 4 rules - other councils bringing in the restrictions include Manchester, Southampton, Plymouth, Loughborough and Nottingham.
Flouting planning and HMO licensing can lead to fines of up to £20,000.