Correcting a mistake

Subject: Apology for incorrect data  

Dear Mr./Mrs./Ms.,

I apologize for the error in the following cost figure. I have contacted the executive committee for correcting the data and hope that I can correct the mistake on time and minimize the cost. 

Personnel                 $2,845,490 (Previous stated $2,843,490) Understated by $2000

Office supplies         $84,500 (Previous stated $43,500) Understated by $41,000

Telephone                $468,240 (Previous stated $186,240) Understated by $282,000

I apologize again for my mistake. I will be more cautious in the future. If you have further questions, please feel free to contact me. 

Explanation: First, I put the subject for my email to make it easy for my boss to view. I begin the letter with my apology to show my sincerity and would like to take responsibility. I organize the cost figure in a way that easy to understand. In the end, I express my willingness to improve in the future in order to show goodwill.