From TAXACT "$100k Accuracy Guarantee: If you pay an IRS or state penalty or interest because of a TaxAct calculation error, we'll pay you the difference in the refund or liability up to $100,000. This guarantee applies only to errors contained in our consumer prepared tax return software; it doesn't apply to errors the customer makes. Find out more about our $100k Accuracy Guarantee."
When I filed my taxes they ran it through all the checks and information, it said I was getting back $3600 and all the information I put in was accurate. The IRS said that I was not entitled to that amount that I was only getting back $2400. I contacted the IRS to find out why and they said it had something to do with the stimulus checks, I argued that I had not received all of them, they stated that I wasn't eligible, however TaxAct's software said I was. When I contacted TaxAct they would not uphold their guarantee, I provided all the information that was proof that I inputted the correct information and the proof that the IRS was saying I was ineligible for that amount. After a lot of back and forth this is the response I got, "Because the TaxAct program calculated your return correctly based on your entries, the Accuracy Guarantee Claim is denied."

"Dear TaxAct® Customer,

We have reviewed the notice you received from the IRS in conjunction with the information we can see in your electronically filed 2020 return. According to the notice, the IRS is adjusting your recovery rebate credit. They provided a list of reasons the credit was reduced.

Some of the items we can verify are correct based on your entries, such as your adjusted gross income being within the income threshold, the ages of your dependents and the actual calculation of the credit itself. We do find that when you originally filed your return, you reported that you received the 1st stimulus payment in the amount of $1,200 and the 2nd, anticipated, in the amount of $1,200. Our records indicate that you are qualify for the recovery rebate credit in the amount of $3,600."

So you can see some of the emails that I sent back and forth with them, I included the notice from the IRS but they still would not accept that it was their software that made the mistake. I've used TaxAct for years but this is the last time. I won't use them again!