I am covered under parents health insurance. They get 1095-C, I don't. But I need to file a separate return.

a 1095-C is not reported by taxpayers so you don't need theirs. 

The only kind of health insurance that must be entered on a tax return is insurance from healthcare.gov  also known as marketplace insurance or "Obamacare."   That is reported on a 1095

A.

   A 1095C is not entered on a tax return at all.

ok. thanks. I still don't know how it affects the dependency. I was depending on them for health insurance, and they are not adding me as their dependent in their return. When it asks if I had health insurance for the whole year, I will answer Yes. When asked about dependency, I will have to say "Nobody is claiming me as dependent, I am not going to claim anyone else as my dependent also"   Is everything fine with this setup? Thanks again

The fact that you are on your parents' health insurance has no bearing on how you answer the question in My Info for yourself when it asks if someone else can claim you as a dependent.  Your parents can carry you on their insurance until you are 26 if they are willing to do so.   That does not affect whether they claim you as a dependent on their tax return, nor does it affect how you answer that question on your own return.   If you do not have marketplace insurance then you do not have anything at all to enter about health insurance on your own tax return.   

 

If you are not sure whether your parents can claim you---here is the criteria they must use to determine whether you can be claimed as a qualifying child or a qualifying relative:

 

WHO CAN I CLAIM AS A DEPENDENT?

 

You can claim a child, relative, friend, or fiancé (etc.) as a dependent on your 2023 taxes as long as they meet the following requirements:

Qualifying child

• They're related to you.
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They're under the age of 19 (or 24 for full-time students).
• No age limit for permanently and totally disabled children.
• They lived with you for more than half the year (exceptions apply).
• They didn't provide more than half of their own support for the year.

Qualifying relative

• They don't have to be related to you (despite the name).
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They lived with you the entire year (exceptions apply).
• They made less than $4,700 in 2023.
• You provided more than half of their financial support