I have a client that claimed the American Opportunity Credit for 4 prior years, but their AGI was higher in those years.  This year it is much lower and they had more education expenses.  They would be better off being able to claim the AOTC this year and LLC for one of the prior years.  Is there anything that prevents amending a prior year return to not take the AOTC for that year (even though eligible) and then take the AOTC in the current year (since they would now have only taken it for 3 years)?