The effect of this provision is that only interest paid in a tax year, relating to the current or previous tax year, is eligible for mortgage interest relief, subject to the ceiling (maximum amount of interest allowed) applicable in the year the interest payment is made. In instances where a borrower pays less than the amount of interest due, then the relief is reduced to reflect the actual amount of interest paid. Where no interest payments are made, no relief is allowed. If the borrower pays the arrears in a later year, then the appropriate mortgage interest relief will be paid in the year in which the payment is made, subject to the ceiling applicable for that year.