Seller agrees to sell to Buyer and Buyer agrees to purchase from Seller the following described real estate in __________________ County, State of Washington. How to Write a Mortgage Deed.Before you fill out your mortgage deed form, write your state at the top. You will learn how to fill out the form accurately to avoid common pitfalls and ensure a legally binding agreement. The general rule is that contracts do not need to be in writing. The exception would be the contracts falling under the statute of frauds. Purchaser agrees to apply for such mortgage loan to at least one lending institution or licensed mortgage broker.