1. In the sample letter, fill in your personal information. I respectfully request that your offices provide me with competent evidence that I have any legal obligation to pay you.If you are making application for credit from STCU you may be notified in the form of a written commitment letter if your loan request is approved. Before you start writing the letter, think about your relationship with the person who owes the money. Is it a friend or relative? Include your name, address, and contact information at the top. The purpose of credit explanation letter is to acknowledge that you had a challenge in your previous life with your credit or maybe currently. Sample Letter of Credit in MS Word format.