Cover Letter with Salary

1. There may be possibility to eliminate you from an interview, if your salary expectations are high and you stated it in your cover letter. But if your stated salary requirement is too low then it will be beneficial for them at the time of salary negotiation. So, carefully think about the salary requirement. You can use approximate range that will provide you number of ways to negotiate later.
2. Mentioning any numbers for salary requirements can create difficulty for you only. So, don't specify it in numbers. Another way to avoid this is, make them to consider your request first. The trick is:
   
   "Instead of giving a salary requirement in this cover letter, I will prefer the salary depending on job requirements and the benefits XYZ Company offer. I would like to meet to discuss the position with you. After discussion we will decide about salary requirements."

If you don't have any idea about salary packages for specific position then you have a best choice for this. Make use of Internet to search what the average salary for the particular the job position. But it's better if you avoid it.