How to Write a Letter of Explanation for Your Mortgage Underwriter

When you apply for a mortgage, your lender will run your finances through a thorough review. This process is called underwriting. Sometimes the underwriter will approve your loan with a few conditions still to meet. One common condition is asking for a letter of explanation.

A letter of explanation is simply a short, honest note from you that clarifies something in your financial history that might look unusual or risky. The underwriter wants to understand the story behind the numbers. Writing one does not mean you did something wrong. It just means the lender needs more context to feel comfortable giving you the loan.

You might get asked for a letter of explanation for many reasons. The most common include a large deposit into your bank account that is not your regular paycheck, a gap in your employment history, a past late payment on a credit card or loan, a recent address change or living situation that is not standard, or a credit inquiry that you did not explain in your application. Each of these situations can make an underwriter pause. Your job is to write a straightforward letter that removes that pause.

Start with a clear heading. Put the date, your name, the loan number if you have one, and the address of the property you are buying. Then write “Re: Letter of Explanation” and the specific item you are addressing. If you have multiple items to explain, write a separate letter for each. Do not bundle everything into one paragraph.

In the body of the letter, state the fact that the underwriter is concerned about. For example, “On my February 2025 bank statement, a deposit of $5,000 appeared on February 10.” Then explain where that money came from. Be specific. If it was a gift from a family member, give the person’s name, their relationship to you, and the date of the transfer. If it was a cash gift from selling a personal item, describe what you sold, when, and to whom. If it was a refund or insurance payment, provide the company name and the reason for the refund.

The key is to back up your words with proof. Attach copies of any supporting documents. For a large deposit, include the gift letter, a copy of the check or transfer receipt, and the donor’s bank statement showing the money leaving their account. For an employment gap, attach a letter from your former employer stating you were laid off or that you left voluntarily, and then a letter from your new employer confirming your start date.

If you need to explain a past late payment, be honest about why it happened. Maybe you forgot, your bank had a glitch, or you were dealing with a family emergency. Do not make excuses, but give a clear reason. For instance, “I was in the hospital for three days in October and missed the payment because I was unable to access my online account. I made the payment as soon as I was discharged, and I have not missed a payment since.” Then show proof of the payment as soon as it was made.

When explaining a credit inquiry, say why you allowed a creditor to check your credit. For example, “I was shopping for a car loan last month and gave permission to three dealers to run my credit. I did not end up taking out a new loan.” Attach a letter from the dealer or a screen shot showing you were rate shopping.

Keep your tone calm and professional. Do not get defensive. The underwriter is not accusing you of anything. They just need the full picture. One or two short paragraphs per item is usually enough. Stay under one page per letter.

Write in plain English. Avoid phrases like “I hereby attest” or “per my understanding.” Just say “I deposited this money because” or “I had a gap in work because.” Use dates and names whenever possible.

Finally, sign the letter by hand. A typed signature is often accepted, but a handwritten signature in blue or black ink looks more personal and official. Scan or take a clear photo of the signed letter and upload it with your other documents through your lender’s secure portal.

A letter of explanation is a small step in the mortgage process, but it is a very common one. Lenders see thousands of these letters every year. Yours does not need to be perfect. It just needs to be truthful, clear, and supported with evidence. Once you send it, the underwriter can check that condition off your list, and your loan moves one step closer to closing.

If you are unsure whether you need to write a letter, ask your loan officer. They will tell you exactly what the underwriter wants. Do not guess. A short, correct letter is much better than a long, wrong one. Take your time, gather your proof, and write with confidence. You can handle this part of the process, and you will be glad you did when you get your final approval.