When you write a letter or email to request a promotion, you'll be able to lay out your accomplishments, qualifications and goals in a format that the boss can review as many times as she wants. That may be followed up by another email or a face-to-face conversation, but in any case, your letter needs to show the employer exactly how you'll help her move the company forward when you're in the new position.

Make Notes

If possible, talk to the outgoing person in your desired position to get a sense of his background and skill set, and what obstacles you may face in the position. If there's a job posting for the position, also review that carefully. Make a list of the qualifications required for the job and note which ones you have. Also start listing your accomplishments that have benefited the company, keeping in mind that the letter's recipients will want to hear what you can do for them -- not why you really, really want the position.

Choose the Right Time

If you're inventing a position for yourself, you'll also need to list key accomplishments that you envision will prove your case -- but it's also about timing the letter appropriately. Often a good time to request a promotion is during your annual or quarterly review, or when things are in flux in your department or company, according to an article published on the Forbes website. For posted positions, send your cover letter and resume through the channels defined on the posting, but also send a promotion request letter to the decision makers.

Find a Point of Difference

Ideally, you're going to show the boss that you not only have all the required qualifications, but that you have something that sets you apart. If you're aiming to be promoted to marketing manager, for example, you'll need the leadership and research skills the past manager had -- but it might seal the deal for the boss to know that you have good working relationships with the team, and that the current manager has taken you under her wing as a mentee. People who get promoted often have mentors who are higher-ups in the company, suggests Randall S. Hansen, Ph.D., founder of Quintessential Careers. Mention those relationships in your letter, and also ask your mentor to put in a good word for you.

Create Three Sections

Much like any other job cover letter, this letter should include three sections.

In the introduction, say that you're excited at the prospect of continuing your career with the company, and name the exact position you want. If you're also requesting a salary bump, mention it, but leave the negotiations about number for later.

In the body, give examples of your past performance and how it's benefited the company. If you have exact figures, such as increased sales numbers, for example, name them. Including specifics and details will help make your case. If you're trying to invent a position for yourself, also name what duties you'll take on and how the new position benefits the company. Also mention your career goals as they relate to the company.

End the letter with a follow-up request, such as a face-to-face meeting. You might also simply tell the boss you'll be getting in touch in person or via email by a certain date.