Before losing it completely, here’s what to think about before raising the issue with your boss.

The type of work. Do you do exactly the same kind of work, and have the same outputs? If your job specs differ, there may be something your colleague actually offers that can justify he or she being paid more.

Work experience and qualifications. In most industries employees can negotiate a salary dependent on their qualifications and experience or expertise in their field. And some people are pros at negotiating a salary – even without much work experience.

General work ethic: Be truthful with yourself, do you  sometimes look at your colleague and think ‘what a goodie two shoes,’ just because they offered to do something that no one wants to do. Do they pitch in whenever necessary? Do you do the same?

Look at their projects: Have they done anything ground breaking to bring more profits in for the company? What are your contributions compared to theirs. It could be more, it could be less, but this can help you gauge whether the pay difference is fair or not.

What is the market rate for your position? Knowing what the industry pays employees in your level, will help you figure if you are sitting on average, above or under when it comes to your salary. Do some research and speak to recruitment agencies about it. If you find out that you are indeed being underpaid, you can include that information when you approach your boss.

• Take a huge breath: Employers make sure that salaries are kept confidential, and if you do stumble upon some info about how much your colleague earns, you can’t really disclose it to anyone, not even your boss. However you can start campaigning for a raise. Fact is, employers pay competitive salaries. Professor of Psychology and Marketing at the University of Texas, Art Markman in his book Smart Change writes about changing your behaviour. He delves into the issue of not asking for what you want, and how really affects your psyche at work. If you ask for less than what you need, your employer will assume that you are happy with your pay.

From asking yourself these questions you can figure out the reasons why your colleague is being paid more than you.

If they offer more, then you can try and do the same. Upgrade your skills, get a qualification etc. If you and your colleague are on par in regards to skills and qualifications, then you may want to put together all of your achievements and contributions so that you can approach your boss and convince them you deserve better pay.

According to Salary.Com, you should make your request for a raise all about you, and leave your colleagues out of it. Showcasing your great work, and leaving out complaints about your colleagues will put you at a better position for a promotion or a raise.