<p>A few schools accept the ACT in lieu of SAT subject tests. I.e. their minimum test requirements are SAT reasoning + some SAT subjects, or ACT. (e.g. <a href=“Standardized Testing Requirements & Policies | Yale College Undergraduate Admissions”>Standardized Testing Requirements & Policies | Yale College Undergraduate Admissions; )</p>
<p>It may be advantageous for a student to take both in junior year, since some students do better on one than the other. That also give a chance to retake the higher one after additional preparation in senior year if desired.</p>