We did not fill it out and our kid received merit aid where we expected him to.

Most don’t require them for merit aid, a few do. Best to ask the school to confirm.

Tulane requires CSS for merit; it’s the only school I found that requires it. I did come across schools that want FAFSA for merit.

We didn't fill it out because we knew we wouldn't qualify for need based aid and the schools our DC applied to did not require them for merit aid.

A few schools require FAFSA for non-need-based merit scholarships, typically to rule out Pell eligibility before awarding a giant scholarship. Emphasis on "few!" Other than that, typically most requirements for financial aid forms involve a need component for the scholarship. Check the scholarship webpages for the colleges in question.

CSS Profile is a different beast. I don't believe any require the CSS Profile for non-need-based merit, though obviously I don't know all possible exceptions, so again, check scholarship websites for colleges.

We will not qualify for FA and we filled both out. Some schools require for merit and instead of tracking who, I just filled them out. Easier to just do it.

Based on income and savings, we know we don't qualify for need based aid, but don't want to leave merit on the table if it's available. Do FAFSA and CSS still need to be completed? I know we've been told it's required at some schools, but most seem to say "required for need based aid". Is there any downside to completing them?