Follow business letter format. Use the official business letter format when writing your letter. You want this letter to be professional.
Understand your employer’s policies. Before you miss work, make sure you know the procedure for letting your boss know that you will be absent. Know whether you need to tell your boss, and how you should get him or her that information (e.g., a phone call, a letter, an email). Also look into how far in advance you need to tell your employer.
Have a legitimate excuse. Be aware of company policy and what constitutes an excused absence from work. Some reasons for missing work may not be approved by your employer.
Send the letter as soon as possible. If feasible, send your excuse letter before you miss work. You want to give your employer time to reassign any of your tasks. If you are asking for a longer leave of absence, send this letter as early as possible. If you don’t have time to send a formal letter, consider sending an excuse email instead.
Keep it brief. Do not go into great detail about why you are missing work (such as a long list of your symptoms, if you are sick, or a detailed story about a personal problem). Instead, succinctly state the day or days you will be absent, and explain (briefly) why.
Offer to help. You might consider helping make up for your absence in some way. For example, you might say that you will still be on email while away, or you might offer to work an extra hour or two later to complete some missed projects. If you can prepare for your absence in advance, ask one or two of your colleagues or employees for help completing any assignments you will be missing. This will be particularly important when you.