Unless, it is from something you don't like to something you do (for instance from "IT Guy" to "Developer" or vice versa depending on your likes). Even then lowering your pay is simply the one of the options open to you. With a little more looking you might find that you can change and increase you pay. You have to be VERY careful because an employer is looking to minimize his expense and maximize your productivity. So, always bargain hard and start high. You can always move your price down, but you can't really move it up.