How do I know if I need to meet this requirement? 

If all of your high school/secondary school education was completed in English, you are considered proficient and do not need to satisfy this requirement.

However, if you've completed all or some high school or secondary school in a country and school where English was not the language of instruction, you will be required to demonstrate English proficiency if you have had less than 3 years of instruction in English.

How do I demonstrate English proficiency?

You can demonstrate proficiency by meeting any of the following exam benchmarks. Keep in mind that you must complete one of these exams by December of your final year of high school/secondary school.

• Score 3, 4 or 5 on the AP examination in English Language and Composition, or English Literature and Composition

• Score 6 or 7 on the IB Standard Level examination in English (Language A only) 

• Score 5, 6 or 7 on the IB Higher Level examination in English (Language A only) 

• Score 6.5 or higher on the International English Language Testing System (IELTS)*

• Test of English as a Foreign Language (TOEFL)* examination:

  • Internet-based test (iBT) or iBT Home Edition: Minimum score of 80 or better

• Duolingo English Test (DET): Minimum score of 115 

• Score of 24 or higher on the ACT English Language Arts (ELA)

• Score of 31 or higher on Writing and Language in the SAT

• Earn a grade of C or better in a UC-transferable college course in English composition (worth 3 semester or 4-5 quarter units)

*Please note: UC does not accept IELTS One Skill Retake or MyBest TOEFL; only the highest composite score from a single sitting is allowed. Also, the digital SAT Reading and Writing section score has not been approved to meet English language proficiency

https://admission.universityofcalifornia.edu/admission-requirements/freshman-requirements/english-language-proficiency.html