Ignore my post above, im wrong, google "TRS citizen information" & check out the page.
I can't post link as im only a new user
Mortgage arrears and payment of interest
While the legislation governing mortgage interest relief provides for granting of relief based on the amount of qualifying interest paid in a tax year, many lenders used to operate the relief based on the amount of interest charged to an account, even if the borrower did not actually pay that amount of interest. This had little impact up to recently.
However, in response to the growing incidence of mortgage arrears, it has been decided that, with effect from January 2014 onwards, all lenders are obliged to grant Tax Relief at Source (TRS) based on the amount of interest actually paid by the borrower within a tax year in accordance with the legislation.
This change does not affect borrowers who make the full repayments on time, in accordance with their mortgage loan agreement.
For borrowers who do not make their repayments or who pay less than the amount of interest charged to their account, the TRS amount due will be reduced to reflect the actual amount of interest paid.
As regards interest-only arrangements, people who are only paying the interest portion of their mortgage are still entitled to TRS and will continue to get it if they meet the qualifying conditions.