Writing a thank-you note for gifts, hospitality or assistance shows you are an appreciative person who understands the importance of etiquette. No matter what your mother-in-law has done to warrant a personal letter, a simple note of thanks will go a long way in strengthening your relationship and making her feel valued. As with any letter, there is a standard acceptable format to follow when writing a thank-you note.
Use nice paper or stationery when writing your note. A handwritten note adds a personal touch and expresses a more intimate connection than a more formal, typed letter. Write a salutation addressing your mother in law as you normally would in person, such as "Dear Judy" or "Dear Mom."
Write a statement that explains what you are thankful for. For example, "Thank you so much for the thoughtful gift token you sent for my birthday."
Explain what the gift or action meant to you in two or three sentences. For example, if your mother-in-law recently took your children out for a day at an amusement park, tell her how much fun they had, and what you chose to do with your free day.
Write a closing statement again thanking your mother-in-law for her thoughtfulness. If applicable, mention sending your love to any other family members, such as your father-in-law. End with a closing salutation you are comfortable with, such as "Love" or "Yours truly," and sign your name.