Temp agencies, which are also referred to as temporary agencies, staffing agencies or temp services, help employers find qualified candidates to fill gaps in employment, such as from employee leaves or vacations, or to complete short-term, project-based assignments. Your ability to negotiate your salary with a temp agency relies on knowing how they make their money. The basic rule is that temp agencies charge the employer a certain rate per hour for each worker, and then keep a certain percent of that fee (usually 25 to 50 percent) while paying the worker the remaining amount. Fees are determined by the type of project and the skills required for each position.

Determine the bill rate that the temp agency is charging the employer for your work. Ask your recruiter from the agency to provide you with this information. If they will not, check with the human resources department at the company itself. If you still are unable to get the information, assume that the temp agency is making the 25 to 50 percent margin over what you are paid.

Research what the going market rate is for the position. You can do this by visiting Salary.com (see Resources) and entering information about the job title, location and your skill level. Print the results and keep this information handy as you move ahead with negotiations.

Update your resume with information that highlights your experience and skills related to the position. This will give you leverage in explaining to the agency why you qualify for a higher rate.

Approach your recruiter at the temp agency. Do not go directly to the employer. Use the knowledge you have gained about their fee structure and the market rate salary for the position and request that they consider negotiating to pay you a higher rate. Your goal should be to achieve 70 to 75 percent of the agency's billing rate. Keep the discussion professional and be prepared to back up your claims with documentation. Many temp agencies are open to negotiation because they get paid when they fill positions and making some profit is better than none at all.