Taxpayers will notice tougher log-in measures when they attempt to sign in to their online tax software accounts over the next several months.

Tax companies, including Intuit, the maker of TurboTax, H&R Block and TaxSlayer, reminded taxpayers Thursday that they’ll need to provide stronger passwords, answer new security questions and face being locked out of their accounts if they have too many failed log in attempts. The tax companies also reiterated that they will share information about suspicious returns regularly with the IRS and state tax authorities to help them catch fraud earlier.

Some of the more significant changes will be noticed by people who use TurboTax, the largest online tax software company in the United States. When TurboTax online software becomes available in early December, users may see new alerts and other security measures intended to make it easier for taxpayers to know if someone has accessed their accounts or stolen their personal information, the company announced.

Most notably, existing customers will be alerted if a second account is created using the same Social Security number. That should give taxpayers a chance to block thieves attempting to use TurboTax to file a fraudulent tax return in their name. If a customer alerts Intuit to say they didn’t create that second account, the company says it will temporarily lock down both accounts until it can verify the identity of the legitimate taxpayer. Previously, multiple accounts could use the same Social Security number and customers would not be notified.

Intuit also said it would alert customers when changes are made to their accounts, which could give them a hint that a fraudster may have accessed their accounts and their personal data. For instance, taxpayers will be notified if someone changes the bank account associated with the return, which could be a sign that a thief is trying to divert their tax refund to another account.

Customers will be told if their password is changed or if a PDF of their tax return is downloaded, a move taken by some identity thieves who took over existing TurboTax accounts last year and used the information on previous tax returns to file phony tax returns that closely resembled those filed by legitimate taxpayers.

The changes were announced on a day when the IRS, state tax authorities and other tax preparers met to warn consumers to be more cautious with their data as they head into the holiday shopping season.  Tax authorities and tax software providers have had to up their security measures after an apparent spike in tax fraud earlier this year. IRS Commissioner John Koskinen has previously said that the IRS stopped 3 million suspicious tax returns this year, 700,000 more than last year.

“Refund fraud caused by identity theft has recently become a more serious and complicated threat,” Koskinen said Thursday, adding that thieves are stealing “unimaginable amounts of personal data” and using it to collect “huge refunds.”

During the upcoming filing season, the IRS will issue weekly tax tips online and through YouTube reminding taxpayers of the steps they can take to protect their identities. The campaign will warn against phishing e-mails and phone scams that trick consumers into sharing their Social Security numbers, bank account information and other sensitive information. The tips will also tell taxpayers to keep their anti-virus software updated and to encrypt tax returns and other files.

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