When you get a job but then find out the employer is offering much less in the way of salary than you hoped, it's always good to remain diplomatic and to sow the seeds for another opportunity in the future. Decline the job offer with tact and respect for the employer -- and leave the door open for renegotiation. In most cases, sending an email or having a verbal conversation with the hiring manager are the most appropriate forms of communication for this type of situation.
Writing the Letter
At the start of your response, thank the employer for the opportunity to interview, and say something you liked about the business. Maybe you had a great time going out to lunch with the boss, or you really like the way the business handles marketing. The point: add some good feelings to the letter. In the second sentence, politely say that you've decided not to take the job, and then say outright that the salary is the reason you're declining. Be positive and humble and don't badmouth the employer, reminds Trudy Steinfeld of Forbes. The hiring manager or recruiter should still walk away with a good feeling about you.
At this point, you can also leave the door open for more negotiation by saying something like "should you be able to raise the salary by X amount, I'd be thrilled to take the job." Do your research into similar positions in your area to name a salary that's realistic. If the employer really wants to hire you, he may come back with a counteroffer. Then sign the letter with a cordial phrase such as "Sincerely," and sign it or type your name at the bottom.