If you've already filed your tax return, part of your reasoning may have been outflanking identity thieves. But according to the Internal Revenue Service, early filers have become prime targets for a different kind of scammer. If you receive a notice or a call about erroneously deposited refunds, get in touch with the IRS immediately. You're being targeted, and you might just get scared enough to cooperate.
Several journalists have already reported getting these notifications, whether it's a phone call alerting you to "arrest warrants," "lawsuits on your name," or even just IRS employees looking to correct a mistake. You're prompted to supply your Social Security Number so your caller can look up your case file, even if you haven't provided your name yet — a clear indicator of phishing. Don't panic if you get one of these calls or a letter asking you to contact an unknown phone number — each article linked here has a good script for dealing with scammers verbally.
That said, if money really has somehow been deposited into one of your bank accounts by an unknown third party, you will have to work with the IRS to return it. The agency might contact you about setting up an online services account to monitor activity taking place in your name. This can include an Identity Protection PIN, a legit program from the IRS.
No matter what, always verify whether you're talking to someone officially affiliated with an institution, particularly when it's asking you about money and identity. The scam may be updated, but there are just as proven ways around it.