Dependent students must report their parents information, as well as their own, on the Free Application for Federal Student Aid (FAFSA) form. 
Find out who counts as your parent when you file your FAFSA form. If you are considered a dependent student for FAFSA purposes , you will need to provide information about your legal parent on the application. A legal parent is your biological or adoptive parent, or your legal parent as determined by the state for example, if the parent is listed on your birth certificate. If you have a stepparent currently married to your legal parent , you generally also must provide information about him or her. View text-only version 

Who is my parent according to the FAFSA form? 
If you need to report parent information , here are some guidelines to help you : If your legal parents your biological and/or adoptive parents, or parents as determined by the state [e.g., a parent listed on your birth certificate] are married to each other, answer the questions about both of them, regardless of whether your parents are of the same or opposite sex. If your legal parents are not married to each other and live together , answer the questions about both of them, regardless of whether your parents are of the same or opposite sex. If your legal parent is widowed or was never married , answer the questions about that parent. 

What if my parents are divorced or separated? 
In this case , how you fill out the FAFSA form depends on whether your parents live together or not. Keep the following in mind as you read this section : For FAFSA purposes , your married parents are separated if they are considered legally separated by a state, or if they are legally married but have chosen to live separate lives, including living in separate households, as though they were not married. When two married persons live as a married couple but are separated by physical distance or have separate households , they are considered married for FAFSA purposes. 

Divorce

user: Would there be any problem if I can't provide the parent information on the FAFSA form?

assistant: Are there any special circumstances that impede you from getting that information?

user: Not really.

user: Just curious on what to do or what to recommend others to do in case I'm confused with some of the questions and circumstances. Like, what to do if the parent doesn't live in the U.S?

assistant: Ok, well, in case your parents live abroad you can select "Foreign Country" from the dropdown box for the question that asks about the parent's state of legal residence.

user: Going back to my question about what to do if I can't get the parent information, What would you recommend on this?

assistant: When you fill the FAFSA form online or in the app, there is an option to indicate that you have special circumstances that make you unable to get your parent information. If you use this option you'll be able to submit the FAFSA form without the parent information.

user: So that option is available both on the myStudentAid app and on the website?

assistant: Yes, that's correct. Whether you fill your form online or through the app you'll get asked if you are able to provide information about your parents.

user: Would that create any disadvantage? to submit the form without the parent information?

assistant: Yes, if you do it like that your FAFSA form will be submitted but it won't be fully processed and you won't receive an Expected Family Contribution (EFC). In this case, you should contact the financial aid office at the college or career school you plan to attend.