They said they try to reach most people by mail first, but if that doesn't work, they'll make house calls, usually for an overdue tax bill, or to tour a business as part of an audit or criminal investigation.
In those cases, they "may leave their business card and a copy of the original notice in someone's mailbox or on their door."
If an IRS officer visits you, he or she will always show you two forms of official identification, including a federal ID.
A business card does not count.
"[The business card and note] didn't really look too professional, but it did have professional tones to it," Robbins said.
Robbins said one of her tax returns was late and she's paying it.