Are my cash balance plan contributions fixed upfront or do they change each year?

Your contributions are not fixed upfront. They will go up or down each year. If your income is higher next year they will go up, and of course if your income goes down then your contributions will go down.

But here is an important point to note. In reality, even though your target contributions will change each year, you will be given a range. For example, your targeted contribution may be $75k, but you may have a low-end range of $50k and a high-end range of $100k. This gives you a little flexibility each year.