Learn more about a mortgage agreement in principle, how you can go about getting an online agreement in principle and more. An Agreement in Principle is not binding for either party.Yes this is standard they want to make sure you can afford it. Complete an agreement in principle online to see if you could borrow the amount you need for a mortgage without affecting the credit score. The approximate cost of the property you'd like to buy. Just fill out the online form with these details and hit the submit button – simple! In today's episode Nicola McKenzie explains what an agreement in principal is, why you need one and how long they are valid for. What do you need to apply for a decision in principle? It takes 10 minutes to complete, there's no credit check involved and is downloadable. It only takes around 10 minutes to complete the form and get a result.