Whether a student is "independent" for financial aid is generally determined by FAFSA rules. (There is a different aid scheme called CSS Profile which is used at mostly selective liberal arts colleges, and yet a third set of rules for low income kids attending Ivy League and similar. I think both of those use the FAFSA "independence" rules but am not certain.)
The FAFSA rules are different from, independent from, and generally tougher than the IRS rules for a tax independent.
People have mentioned the age of 26. Age is one way for a student to become independent under the FAFSA rules, but it's age 24 for FAFSA, not age 26. Age 26 has to do with remaining on the parents' health insurance under the ACA.
There are other ways for a student to become independent: get married, become an orphan, join the armed forces, finish undergrad and start working on a graduate degree. See the FAFSA rules for all the details.
BTW, the FAFSA rules are changing starting next school year (2024/2025). Google "FAFSA simplification" to read all about it (warning: it's complicated and a bit messy in terms of the implementation). I don't know if they've changed much in terms of the rules about when a student is independent.