Being a good boss is harder than it looks. CEO coach and former Google executive Kim Scott would know. After working as an executive at Google, Scott became a sought-after CEO coach in Silicon Valley, advising C-suite clients at Dropbox, Twitter and other top companies. She's helped dozens of managers through both the exciting and dreadful parts of their jobs — chief among them, firing an employee. "It goes without saying that getting fired is one of the most soul-challenging things that can happen to a person," Scott writes in her new book "Radical Candor." So, she says, leaders must be thoughtful about the decision. According to the leadership expert, here is how to know when it's time to give that employee a pink slip.

Kim Scott, former Google exec and CEO coach. First Round

1. You've clearly communicated the issue with their performance on multiple occasions According to Scott, the best way to be a good boss is to be direct about an employee's performance — when it's good and when it's not. Make sure that you've communicated the problem clearly. If you have doubts about whether or not you've done so, then you probably haven't, the CEO coach says. When somebody is performing poorly, has received clear communication about the problem numerous times and still isn't improving, Scott says, then it may be time. 2. You've challenged the employee to improve on numerous occasions, and have offered to help Even if the employee has explicitly been told about the problem on multiple occasions, he or she may still be scrambling to find a solution. "Have you been humble as well as direct in your criticism," Scott writes, "offering to help her find solutions rather than attacking her as a person?" If the answer is that you have indeed offered to help — and more than once — then things are not looking good.

Getting an outside perspective can help you make sure you're being fair. Kim Scott author of "Radical Candor"