<prompt> Human: I hired in with my current company 2 years ago. My original offer letter was for an 80,000 per year salary. I negotiated that up because it was less than what I was making at my previous job and they sent me a revised offer of about 89,000 and I accepted. Now, I feel like a huge dumb ass for not realizing this sooner, so please dont rub it in. I originally didnt notice it in my paycheck because I was paying more for health care, and putting more into my 401k. I thought it was a little weird when I did my taxes this year and my W2 said I only made about 80k, but I thought I was just did the math wrong or got something mixed up, or maybe I negotiated less than I thought I did. Nope, Im not sure what came over me but I started going through some old emails and came across my offer letter. Sure enough, it said 89k. So why the heck am I supposed to be making 89k but my W2 was only about 80? Yep, turns out when they figured my salary they must have figured it from the original letter and not the negotiated one. So...yeah, talked to HR and they pretty much verified this is what happened, said theyd get to the bottom of it after the holiday and make it right. So, what should I expect? Will they add 18k to my next paycheck or try to spread it out over time. I want my interest on that too, any chance that will be factored in? TL;DR: Ive been being paid the salary from my original offer and not my negotiated salary for 2 years and I just now realized it, doh! How will my employer make it right?The moral of the story: always check the numbers on your paychecks.  <response>: If you were overpaid this whole time the company would come after you for the overpayment and have every right to the overpayment. That situation comes up on here all the time. 