When I ask managers to tell me the biggest mistake people make when they ask for a raise, the answer is that employees try to use their personal financial situation as a reason to get a raise. For example, one manger said her employee bought a new car and then asked for a raise because the monthly payments were too high for her to handle.
That may make perfect sense to the employee. Unfortunately, it won't help your manager give you a raise.
Everyone at work wants more money to spend. We want to be able to move to a nicer place, put our kids through college or even take the vacation of our dreams. That's not a good enough reason for your manager to give you a raise. Usually your boss has to get approval from his or her manager, Human Resources and maybe even a raise committee. Imagine your boss telling his or her manager that you want a raise just because you'd like to make some more money so you can pay for a great vacation. What do you think the response would be? Probably not positive.
Yes, you may want a raise to pay for your new car, but that's not what you should say. Instead you should focus on the business reasons why you should get a raise. That will make it easier for your boss to sell the idea of your raise to other people that have to approve it. Companies pay for performance and that's what you need to focus on.
Privately your boss may be sympathetic to your need for more money, but that's not going to get you very far with your raise request. Or your boss may get annoyed that you brought up your problems handing your personal finances. In either case, you'd be better off focusing on the business reasons for the raise.
So the next time, you want to talk to your boss about a raise, make sure you avoid the biggest mistake that people make - discussing personal financial needs. Instead, focus on what you have done for the company. It will make getting a raise much easier.