There are two separate questions.
1. Can you be claimed as a dependent?
2. Will the person who could claim you actually claim you?
The second question only relates to the American opportunity tax credit for college students. In some cases, a student who can be claimed as a dependent can still qualify for the AOTC if the parent does not claim them. The second question has no effect on any other part of a tax return.
The first question, can you be claimed, affects several tax provisions, and in 2020, this included preventing the person who can be claimed as a dependent by someone else from receiving economic stimulus payments or the recovery rebate in their own name. You must answer yes if you meet the qualifications, regardless of whether the person who could claim you will.
If you don’t meet the qualifications, you can answer no. You should be able to easily amend your tax return to change the answer from yes to no if that fits your actual situation. On your 2020 tax return, that will result in the addition of the recovery rebate, assuming you did not previously receive the stimulus payment. If you did previously receive stimulus payments, then changing your answer won’t change anything on your tax return, and the software will not allow you to file an amended return that does not change your refund amount or tax due.
