Just to explain my question a little bit. I know that if you owe the school money they are allowed to withhold your diploma and transcripts. My real question is if this is the situation and the college happens to change requirements for the degree before you fulfill your debt can they revoke the degree to make you take the classes needed?
Yes, as you say, it is common that a university will refuse to issue a diploma or transcripts until you have paid them what you owe.
However, I've never heard of them making you take more classes if requirements change in the meantime. Most universities have a policy that what you have to fulfill are the requirements as they were listed in the catalog of the year that you first entered the university / degree program. The university can't change them retroactively.
But you'd better read your university's policies to be sure. This should be explained in the course catalog.
What you're suggesting could happen, but it probably pretty rare in practice. Your school's policies will typically spell out the exact graduation requirements, including what happens when degree requirements change.
For example, My undergraduate institution officially recorded the "catalog description" of each degree every year. When changes to the degree program occur, they only happen through changes to the official catalog description. The school's policy was that you were allowed to graduate under any catalog description for a year in which you were enrolled, for catalogs up to 7 years old.
Suppose I enroll in school in academic year 2015- I'm entitled to graduate under the 2015 requirements up through the 2021-2022 academic year. If I'm enrolled for four years, then I also have the option of graduating under the requirements for 2016, 2017, and 2018 if I so desire. The intent here is that your degree program cannot unexpectedly become more difficult to finish, as long as you finish in a timely manner.
This is pretty standard in the US as far as I know.