If you are offered a job you do not wish to accept, you should politely decline the job in writing. Take care to write a rejection letter that will avoid burning bridges with the company making the offer. Make sure to convey sincere appreciation for the company's time and efforts.
Format your letter like a business letter. Address your letter to the person responsible for making the offer. Make sure to address the person who wanted to hire you by his or her full name.
Add your full contact information as part of the letterhead, including your phone number, home address and e-mail address.
Start your letter out by expressing your gratitude. Open your rejection letter by explicitly thanking the individual (and company) for making the job offer. Then, if possible, clearly state a reason why you are unable to take the position. Make sure that your reason is clear and concise. For example, write "I am unable to accept the job due to having taken employment with another company." If you do not wish to mention why you do not want to take the position, avoid doing so.
Avoid insulting the company. As stated before, burning bridges with a company may hurt your career in the future. Even if you do not feel that you ever wish to work for the company, abstain from speaking negatively about it. After all, you never know where you might encounter the employees at a future time in your professional field. Keep your rejection firm but polite. Leave no ambiguity as to what you wish to do.
Exercise diplomacy. If you are rejecting an offer due to having previously accepted one at another company, stay away from mentioning specific details. Show diplomacy to the company's hiring manager.
Close your letter by thanking the person and company for its time. Send the company your wishes for its future successes, and end your letter with a courteous closing such as "Sincerely yours," or "Best regards."
Be prompt. Never leave a company hanging regarding whether you are going to accept a position with them. As soon as you have made a final decision, write and send them your rejection letter. This avoids holding up the company's hiring process, which can sometimes take quite a long time. To be professional, always type your rejection letters, rather than writing them out by hand.