A transfer letter is a written request, usually to your supervisor, asking for permission to work within a different area of the company. This is not necessarily a negative thing, and does not reflect negatively on the supervisor or office staff. Most often, a transfer letter is written to prevent the monotony of staying in the same position, or to explore new opportunities within a different facet of the same company.
Write your name, current job title and address on the top left corner of the page. A transfer letter is a formal request, and as such should be done according to formal letter conventions.
Leave a line below your personal information and write your supervisor's name, position and work address -- as you did your own. If the letter will be going to Human Resources, or to another individual, write their name instead. Leave another blank line and write a standard greeting: "Dear so-and-so,"
Get to the point and ask to be transferred. State the location you wish to go, whether it is a different city, or simply a different position within the same office, and give the specific reasons why. Try to appeal to the recipient's soft-side and do not implicate anyone in your decision.
Explain why the requested position would be ideal for you. This should be written like a cover letter for a new job. You are selling your abilities to your supervisor. Just because you have a job with the employer already does not guarantee your success. Think of it more as a foot in the door.
Praise the company and the opportunities they have given you this far, but be sincere. Do not go over the top or it will look like you're sucking up. Tell them you appreciate everything that they have done for you so far, and reinforce your loyalty to the organisation.
Thank your supervisor for her time and consideration and close with a standard farewell such as "Sincerely,". Sign and print your name below.
If possible, deliver the letter to the recipient personally and explain to them that you are happy to discuss the issue further, if they wish.