It sounds like you have jumped to the finish line before running the race. You are not finished in this job. In fact, rather than looking for a job, you are looking for money in a job you currently enjoy, and that should be the topic of a discussion with your boss.
Before doing so, it is important to remember that research on pay levels can lead to some mixed messages. For example, another company may be paying more for the same job, but perhaps the benefits are grossly inferior or the company may be a totally undesirable place in which to work. Be sure to compare apples with apples, and not apples with lemons.
If your research still indicates that your paycheck is not up to par, then you should tell your boss that you are concerned with the comparability and equity of your pay. You can provide some specific data, but be sure to mention any points that demonstrate the value that you add to the organization, such as your productivity, expertise, continuing education, or informal leadership.
If the pay issue is not resolved and you decide to leave as a result, you can say so to a potential employer. In fact, this can be interpreted as a sign of confidence and self-worth on your part, and that can pay off in a job interview.
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