I'm a software developer based in the U.S. I've been with a company for a few years.

I have 8 years of work experience, but I'm doing the work that someone with 15-20 years would typically do. My management has told me this themselves. However, when the topic of promotion or raises comes up, I've been told that paying me is tricky because I don't actually have 15-20 years of experience and management can't figure out how to pay me.

I'm consistently given more work and get good reviews every year. So, I think people trust me to do the work and are happy with the results.

Is this normal? Are companies normally this strict when it comes to number of years worked and how much you can get paid based on that number? Nothing signifies that in my work contract which is why I'm asking if this is a normal practice.