Write this type of letter to apologize for lying to someone. Include any details that are relevant, such as what you lied about and what the truth is. Also mention how you plan to fully resolve the issue.
[Your letterhead, if desired; if not, your return address]
[Date of letter—month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
I am writing to express to you how sorry I am for lying to you and telling you that I had completed all of the household chores that you had asked me to do, even though I knew that I had only completed a small part of them. It is really out of character for me to be dishonest or insincere like that, and I hope you will forgive me. In the future, I promise that I will be straightforward and honest with you, and I hope your trust in me will be restored.
Also, by the way, I have now completed all of those chores. I would like to do some extra chores this week as a way to show you how sincerely I regret making this mistake, so please let me know what tasks you would like me to do. Thank you for listening and for graciously considering my apology.