As a landlord or a property investor, you are able to claim interest relief by offsetting it against your lettings income. So even if you have an interest-only mortgage or a repayment one you can still claim the interest.Also if you take a personal loan and you use it entirely for the purpose of your rental business, you can claim the interest on the loan as an expense.
Very important to remember is that you can only claim interest against a loan up to the value of the rented property when first let. The capital account cannot be overdrawn.
There is a possibility to re-mortgage for a greater amount and claim this when the additional amount is used for the purpose of an investment property or wholly and exclusively for the business property.
You can claim interest on your mortgage even when your property is empty.You do not have to split the interest on the mortgage if you are genuinely trying to let the property but it is empty because it has not been able to find a tenant. In this case the interest will meet the ‘wholly and exclusively’ test. It will not meet this test if you have not been trying to let the property or you have been using it for private or non-business purposes .