I am not sure what you mean by under her old account, but if her social security number was used then it is indeed fraud and you need to call the IRS. This happened to my wife and I, where someone filed a joint return using her name and social security number as the spouse! When we tried to submit our return, the return was rejected with no reason. We ended up calling IRS to find out why. After about an hour on hold they answered and referred us to their fraud section which took another 45 minutes to answer (and this is all before COVID). Nonetheless, the person in that department was very helpful, first verifying my wife's identity over the phone by asking some questions as such, and then they fixed the problem, but told us to have her freeze her credit for some time (forget how many months). And since then they have sent us a special Personal Identity PIN number in the mail (make sure you save it and take a picture in case you lose the paperwork) which we have to input before we file out taxes which TurboTax does NOT suggest as part of the step by step process, but you have to find it using the search function, which caused rejection of next year's taxes, until we found out that was the issue and how to enter it.
Hope this helps.
