The amount of interest due between the date your mortgage starts and the date the first mortgage payment is calculated. Sometimes, there is a gap between the closing date of your home purchase and the first payment date of your mortgage. Let’s say that the closing date on your new house is August 10th – but your mortgage payments are on the 15th of each month (so your first payment is calculated from August 15th and paid on September 15th). That leaves five days (August 10th to 14th) that aren’t accounted for in your first mortgage payment. You have to make an extra payment to make up for these five days; the payment is generally due on your closing date. You can avoid all this by arranging to make your first mortgage payment exactly one payment period (e.g., one month) after your closing date.