From April 2017 landlords have begun to lose the ability to claim tax relief back on their mortgage interest at the rate they pay income tax, particularly those who have borrowed heavily.
One way that landlords have been able to circumvent this issue is holding properties within a company, where different rules apply. Landlords can use limited companies to buy the properties from themselves and paying corporation tax on letting profits can still be more tax-efficient. However this solution has its associated disadvantages, such as Stamp Duty Land Tax of 8% payable on the re-purchase.
A decision to make a change of ownership like this should only be made after taking proper advice on the particular legal and taxation implications.