Office Halloween parties can be scary for employees if they choose a costume that's too risqué or offensive.

"Halloween parties often do not get as much attention as other holiday celebrations in the office, but the costume element actually adds an extra element of risk for employers," said Atlanta attorney Josh Viau with Fisher Phillips. "To address this added element, employers should be sure to clearly communicate their expectations beforehand."

Viau said costume choices could violate dress code and other policies, such as the non-harassment policy.

"Some costumes, such as dressing like a 'killer clown,' although not sexually or racially inappropriate, can still be offensive," he explained. "Political costumes that cross the line can also cause problems, not to mention foster heated discussions that could turn the mood of the party sour."

Viau said employers should consider alternatives to costume parties..

"And if an employee ignores the warnings, the employer must be prepared to follow through with appropriate discipline," he added.