Hi! I'm taking a gap year next year (I'm going to move to Brazil's biggest city with some friends and dedicate myself 100% to my startup). I'm planning to take TOEFL and SAT Subject this year and take the ACT only next year. Is there any difference for colleges about taking the test this year or next year?
It won't matter to colleges whether you take the ACT this year or next year. You'll have fewer chances to retake the test if you wait until next year, but otherwise it's not going to impact your application. Just make sure you're aware of the differences in test dates (there's no international testing on the February date) and fees if you're taking it in Brazil!