Roth IRA contributions

I've had a Roth IRA since about 2000. I always report my annual contributions, which I understand the IRS needs so they know how to tax when I begin to take distributions. Recently I've downloaded 1099 forms from my broker to report. Some years I get a credit or deduction for my contribution, and I just accept whatever the online system gives me. Do regulations change from year to year? What is allowed?