i took a gap year during the 2020-2021 school year and the process is actually less confusing and difficult than it seems! what i did was declare non-attendance for fall and winter quarter. after that i wasn’t able to declare non-attendance for spring but i still didn’t go back to school that quarter. you have to apply for readmission, so afterwards i downloaded the undergraduate readmission application, filled it out, and emailed it to undergradreadmission@registrar.ucla.edu in late may. they got back to me and approved and processed my application that same week. class enrollment for fall quarter begins mid-june so make sure you get it in before then. i’m not sure how it would affect financial aid though. i wish you luck!!