This offer is subject to valuation and contract and is valid for 30 days from the date of this letter. In arriving at this offer we have taken into account the updating work that is needed.Do you know how to write an offer letter for a house? We're here to teach you the ins and outs to improve your chance of closing a deal. The offer letter gives you a reason to own your offer and explain your reasoning behind it, so vendors cannot take offence if it is a bit cheeky! GCAAR MEMBERS ONLY – Download all the contracts, disclosures, and forms you will need for a real estate transaction in Montgomery County, MD. Copies of the Montgomery County Landlord-Tenant Handbook are available online at.