Before we answer the question of whether jeans are business casual or not - what exactly is business casual/biz casual? This concept is everywhere but is so ambiguous, it becomes hard to explain.
Business casual is the concept of mixing casual wear with smart components of a professional suit.
The measure of professionalism within women's business clothes can be challenging however, there are definitive dos and don'ts that can help clear things up.
The same concept applies for jeans within a business casual outfit. Jeans aren't ruled out of the business casual degree completely. Instead, there are rules in place that keep jeans professional enough to count in an office environment.
Jeans can be worn for business casual!
But... there are conditions:
Wear a professional blazer with jeans
Wear an informal cami or tank top with jeans
Wear dark jeans, the closer to black the better
Wear ripped jeans
Wear office suitable shoes
Wear high fashion accessories with your jeans or boyfriend fitted tops
Not every office will approve jeans as a business casual item. However, as a general rule, jeans can be business casual, as long as they are within the dos. Make sure to scope out your office strictness before wearing jeans on a business casual day. Don't wear jeans on the first day!