Is it possible that, for example, your FAFSA calculated an EFC of $10,000, and you would be given a need-based aid of $15,000 based on your EFC but after the public university looks at your CSS profile and sees the value of your home and your parents retirement accounts (that are all totally disregarded for FAFSA calculation), the school would decide that you need less of financial aid, and not give you the $15,000 need-based aid.
In other words, is it possible that a public university would decide to DEcrease the financial aid package offered to you as a result of me submitting (non-required) CSS profile, and therefore I am better of submitting just FAFSA and NOT submitting my CSS profile?
If the school does not require CSS profile, then don’t send it. It costs money you know.
But FAFSA only public schools usually don’t meet full need.
Did you run a net price calculator on the college website? Where did you see that you might get $15,000 in need based aid from a public school? Is it a merit scholarship? Those are usually not tied to need.
But if you had a $0 EFC the most federal aid you qualify for would be a $5800 Pell grant, maybe a small SEOG grant, some work study, and student loans of $5,500. Maybe a state grant as well.
Are you applying to a public university that REQUIRES the CSS Profile? If yes, you need to file it to get institutional aid if you want to be considered for that. No choice.
I doubt there is even a way to get a non-Css school to look at a CSS application. If a school has a limit of 2 LOR and you submit 5, should you get bonus points? If the essay is limited to 500 words and yours is 1500, should they accept it and compare you to the student whose essay was 498 words?
If FA is awarded based on the FAFSA, that’s what it is based on. You can appeal the FAFSA findings, you can follow the appeals process, but the appeal is not done by submitting the CSS. The CSS might be useful to organize the information, to prompt you to mention that you have big medical bills or business losses or some other one-time financial event.