When you're asking for a promotion, the standard way to do it is to meet one-on-one with your boss, laying out the reasons in person. Often, bosses won't be willing to give you an answer right then and there though, and that's where your persuasive essay -- really more of a letter -- is going to come in handy. The ideal letter will remind your boss why you're worth promoting long after your meeting is done. Like all persuasive letters, it should talk about your accomplishments and your contributions to the company, while keeping personal arguments to a minimum.
Begin your letter by thanking your boss for the opportunity to work with him. Don't gush; just briefly express your gratitude. Then state your intention for a promotion to a specific position. You might say something like, "Because I so enjoy working here, it's my intention to work here long-term in X position." Your boss will appreciate you getting right to the point.
List your Accomplishments
In order to get promoted, you have to establish your value with the company. Start doing that in the second paragraph. Before you write the letter, make a list of your biggest accomplishments in the company, and then try to quantify them. For example, don't just say, "increased sales," but instead, say, "increased book sales by 10 percent in two months." Then list three of your main accomplishments -- or the ones that will pertain to the job that you're now pursuing -- in the letter. Be specific and confident. Say something like, "I am well-suited for the position because…" and then list what you've done.
Personal Issues and Threats
If you need help deciding what's important for the position, look at the biographies of other people who do it, or read past job postings to find out what the company is looking for. Whatever you do, don't list personal circumstances as a reason for the boss to give you the promotion, as that's not what your boss cares about. In these types of negotiations, don't make any threats or mention that you're considering other jobs, reminds Wake Forest University's Executive Director of Personal and Career Development Dr. Katharine Brooks in an article in "Forbes."
End with Action
As with all persuasive essays, yours should end with a call to action. Don't make threats of leaving, as that's not going to motivate your boss. Instead, mention that you'd like to hear back by a certain date, or that you'll be calling for another meeting within a certain length of time. At the very end of the letter, restate your commitment to the company, and sign the letter cordially.