I work with companies all over the world and have helped started up a couple of companies as well as the small one I run. I want to have focus on what I am saying and not create dissonance between how I look and how they expect that I will look, so I try to largely match their code but at the high-end (they typically think they are paying us very well so the clothes ought to look expensive, though I buy everything on sale). So, I am a bit of a cultural anthropologist about how people in offices dress.
Business casual means different things in different places. I always want to fit in, so when I am going someplace new, I have my assistant call and ask what the dress code is there.
In some places, they still wear suits and ties. I do a fair bit of work in the UK and unless you are meeting with the CEO/EVP level, the basic uniform at most of my clients there is a suit but no tie. In the US, ties are a lot less frequent but in Asia, my clients will be wearing ties except for at off-site meetings. I was just at a meeting in Switzerland and the top guy at the meeting, a C-Suite guy, wore a tie while two other males (American) wore suits but no tie and a Brit wore a tie but no suit jacket. (I wore a suit and tie because at the prior meeting with Mr. C-Suite, he wore a tie).
In the US in most corporate settings, business casual used to mean slacks, a button-down shirt and a sportcoat/blazer. Now it is much more slacks (sometimes but not always including khakis) and a well-pressed shirt but in some companies can mean a polo shirt also (and some not).
I helped start up a quantitative hedge fund and introduced several very large hedge funds to the firm who became its investors. I would warn the investors that the team (other than the guy who ran the firm) thought getting dressed up meant their t-shirts didn’t have holes and so they should dress however they wanted but not to dress up on our account. My son’s software startup had a similar dress code, but he would dress up for external meetings. A friend set up a meeting for my son with the CEO and BD guy for a successful larger startup. He wore a suit with no tie and they sort of teased him as they were wearing t-shirts.
Given the variability, I would suggest, as ucbalumnus did, that the best approach is just ask the dress code. If you just ask generally, they will say business casual. So, I ask explicitly, “Does business casual mean a suit with no tie, slacks and a blazer, slacks as a buttoned down shirt, khakis and a golf shirt, or jeans?” Sometimes, it is useful to ask a female as women may be more observant.
