First of all, stay calm.
Next, don't run to your boss and demand a raise, said Katie Donovan, a salary negotiation coach.
"If you do find out that others are earning more, do not rush to your manager demanding more 'because so and so earns more,'" Donovan told Business Insider.
Anna Cosic, career strategist, agrees. "It's important to note that the information you eventually gather is not intended to be used towards HR or your manager saying that since X is making Y, so should I," Cosic said. "That rarely pays off and they may have several different reasons that someone makes more than you do."
Plan out a meeting with your boss in which you show why you deserve to make more. As we've previously reported, any good salary negotiation presents a case for your promotion based on data.
That data should show that you have excelled in your role. Vicki Salemi, career expert for Monster, told Business Insider you should already know the quantitative ways that your company measures performance. Think sales goals, output, or another barometer.
It also might include qualitative information, Salemi said. If you led training or became a trustworthy person during a year with tumultuous office politics, you should include that in your discussion.
That data should also show that the number you're asking for is on par with what folks in your position normally make, if possible.
When you talk to your boss, don't say that you know your coworkers make more than you do - and definitely avoid name dropping or number dropping. That could cause negative repercussions for your coworker.
When it comes down to it, your company "may have several different reasons that someone makes more than you do," Cosic said.
Instead, MarketWatch suggests saying something like: "It was brought to my attention that the market value for my position is X."
That way, you can protect your coworkers while still (hopefully) securing more money for yourself.
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