Many twenty-somethings are just filing their tax returns for the very first time. Unless they are informed about how the IRS works, they could easily fall victim to the IRS phone scam.
Let your children know that the IRS will NEVER contact them by phone. If there is an issue with their tax return, the IRS will send a notice in the mail. If your child does receive a call, tell them to not share any information, or answer any questions, but to promptly hang up—no matter how threatening the person on the other end sounds.