Your first Direct Debit may be more than your normal on-going monthly repayments. This is an industry standard practice, as your first payment includes what is known as initial interest. Initial interest is the interest charged from the date of completion, up until the end of that month. If it is not possible to collect a payment in that first month the initial interest will be added to the following month so could cause the payment to be much larger than your regular payments. It is advisable to budget for this when you are moving home.