The first paragraph of your promotion letter should focus primarily on announcing to the employee that they have been promoted to the position of ________ effective (date).
In the main body of your letter, express your appreciation for the hard work and dedication of the employee. Express your approval of their work and why you recommended the employee for the promotion, including facts or details surrounding why you chose them for the job.
This area of your promotion letter should include details of the promotion, including when the employee is expected to resume the position, responsibilities, pay rate, when they will be eligible for a performance review, who they will report to, etc.
The concluding paragraph of your promotion letter should include your thanks for a job well done; also congratulate the employee on their accomplishment, and wish them well in their future endeavor.
Writing a promotion letter is a fairly simple and straightforward task. Using the tips and guidelines above, you should be able to construct a letter that is professional and includes all of the pertinent information necessary for the employee to clearly understand their new position and what is expected of them.