When it comes to what is considered a big purchase during underwriting, there are a few things that you will want to keep in mind. First and foremost, the amount of money that you are borrowing will play a role in this decision. If you are borrowing a large sum of money, then it is likely that the lender will consider this to be a big purchase. Additionally, the type of property that you are buying may also be taken into consideration. If you are purchasing a home or a car, for example, these are typically considered to be big purchases. Finally, the down payment that you are able to make on the purchase will also be taken into account. The larger the down payment, the more likely it is that the purchase will be considered a big one.