Writing a leave letter to an employer is a very simple and straightforward task. It is necessary to keep the letter short and concise while stating the reason in clear terms. The tone of the letter should be formal and not casual.
In the body of the letter you should mention the exact number of days you want to be absent from work, with dates. You should be able to give the exact date of resuming work, so that the employer is clear. Reason for the leave should be stated in clear terms and it should be a valid reason.
You could also add details of all the projects that you are handling at present and the status of the same. This will give a clear idea to the employer about your work schedule and of any important deadlines. You could also state that you have handed over the projects to your colleague.
You end the letter by thanking them for considering the application and also by giving your contact numbers, if possible, for the leave period. This will help them contact you in case of emergency.