There are two types of adjustments for which a buyer can be charged on closing;  

• Prepaid services. Where the sellers have prepaid property taxes or certain utilities, the buyers can be charged for the amount of prepayment on a pro-rata basis, depending on the date of occupancy. For example, if the sellers have paid the property taxes to the end of the year, and the sale closes on October 15th, the purchasers will be charged with an adjustment of 77/365'ths (the number of days remaining in the year) of the total paid for the year.

• Interest. This is the amount of interest required to be prepaid up to the Interest Adjustment Date (IAD). IAD is the point at which the mortgage interest starts accumulating "in arrears". In Canada all mortgage interest is calculated and paid after the period to which it applies. This differs from the way in which rental and lease payments are calculated, which is "in advance". The good news on this one is that if you prepay for say 3 weeks you won't have to make your first payment for almost two months. Also, if you take a biweekly payment term, the longest interest adjustment period is less than two weeks, by definition.