Right around this part of summer, many businesses face an annual challenge: as the temperatures start rising, the distinction between "business casual" and just plain too casual in the office is easily lost. How do you ensure that your people look professional and protect your company image without being too draconian about the rules?

According to a recent study conducted by staffing agency Robert Half International, 74 percent of companies surveyed choose not to alter their annual dress code for the hotter months. That's one solution. But what about if you want to be a bit more lenient?  

"A [summer] dress code is necessary, period," says HR specialist and Inc. columnist Suzanne Lucas. "It's either appropriate or it's inappropriate, and it doesn't matter how hot it is."

The Summer Dress Code 

When it comes to how to define what's appropriate and what isn't, Lucas doesn't mince words: "There are what I call the three Bs: No Boobs, Butts, or Bellies."

In other words, this is about how much skin employees can show around the office.

Lucas does deem sandals generally acceptable, although wardrobe stylist Kristen Kaleal warns of the caveats: "If you work in a liberal footwear environment you should be grateful, but guarded. Always have well-groomed feet. If you're going to wear sandals, make sure they are of a higher quality (leather is always a safe bet) and that they have at least a small heel or wedge to give your feet the support they need. Sandals shouldn't be ridiculously high, but they shouldn't be totally flat, either." 

Kaleal and Lucas both agree that sundresses can be office appropriate-- provided they are worn with discretion, and don't violate those "three Bs" of summer code. They should be knee-length at highest, and paired with a cardigan or blazer if the environment is on the more formal/corporate side.

In the end, Lucas admits: "There will always be somebody who finds some way to be completely inappropriate at some time. That's what makes [summer] dress code so complex." 

How to Handle the Rebels 

Beware: Addressing a violation of the "three Bs" is always a tricky situation.

Lucas says that if a male superior comments on his female employee's wardrobe, for instance, he should make sure that his wording does not verge on sexual harassment. Better yet, Lucas advises that he have a female manager handle the situation, as these instances may be "emotionally fraught" in ways that they wouldn't be with a male employee.

While every company has a legal right to tell employees what they can and cannot wear, employees also have a legal right to feel safe and comfortable in their own work environment.