Funding / financial aid question

[applicant1234]

Hello,

I'm applying for PhD programs currently and I am a bit confused about how the financial aid works. Do I need to submit some sort of financial aid form to the schools to which I'm applying in addition to their regular application by the deadline? Or do schools make choices based on the application alone (on which, when asked, I say I'd like to be considered for RA, TA and list a fellowship I've applied for, but that's about all that is related to financial stuff) and then ask for the financial information in the spring? I've seen a few posts on the site that say things like 'admissions will be difficult especially if you're asking for admission with full funding,' and that confuses me, because how does the school know what funding you are 'asking for.'

In general, I now have this fear that there's a financial aid application that I should be submitting by the deadlines that I am totally missing, and that will mean my application is 'incomplete' or something like that.

Thanks for any responses!