Clause 24 of the Finance Bill sets out restrictions for individuals on claiming mortgage interest as a cost against their property investment income, for individuals it will work as follows
2017/18 75% of the interest can be claimed in full and 25% will get relief at 20%
2018/19 50% of the interest can be claimed in full and 50% will get relief at 20%
2019/20 25% of the interest can be claimed in full and 75% will get relief at 20%
2020/21 100% will get only 20% relief
These rules will not apply to Companies, Companies will continue to claim full relief.
The rules also don’t apply to Furnished Holiday Lets.
Essentially Section 24 removes Interest from the property expenses and gives you tax relief at 20% (basic rate). So Higher rate tax payers will pay more tax.
The Mortgage Works have a spreadsheet calculator that demonstrates this and also incorporates other profits and income.