When you are approved for a mortgage, you will often sign a document that states that they can revoke your approval if your creditworthiness changes before the mortgage is funded. Most people don’t think anything of this, if they even notice it, but it is actually quite important. If you buy a car, or open a new credit card, or sometimes even borrow more money on your existing credit line, that is a change in your creditworthiness, and it can affect your ability to close your mortgage. Your best bet is to hold off on any change to what you have borrowed until after your mortgage has funded.