The letter must outline your complaint, the harm you suffered, and how you want the problem resolved. This is called a 30 Day Demand Letter.A demand letter: Give your landlord a chance to return your deposit without having to go to court. Or try the MassAccess interactive interview. Learn how to fill out a Financial Statement Form, which you need for many types of cases in Massachusetts Probate and Family Court. Click below to submit documents for an existing claim. File Demand Letter Massachusetts. Fill out a simple, secure Demand Letter questionnaire, and Fast Legal Form filing handles all the legal form filing work. If you feel stuck and are considering selling your house for cash, we buy houses! Fill out our short form below to get your cash offer today!