Once you normally have a mortgage, your lender will do a mortgage appraise to make sure the property you buy is worth the price you pay. You can ask them to change your first payment date over the phone or online. To apply online, you will need your mortgage account number and the postal code of the property you have mortgaged. RBS is currently offering £250 in cashback to first-time buyers on the day you withdraw your mortgage. RBS has sold PPIs to customers with mortgages, credits and credit cards. You can view, manage and track the details of your RBS mortgages via the RBS online portal. Your RBS mortgage is your last name, date of birth, mortgage account number and postal code of your property.