It's not a law. It's a TurboTax restriction. TurboTax does not handle any amounts larger than $9,999,999 for any purpose. TurboTax is designed for ordinary taxpayers. It's not designed to handle high-volume stock trading, exceptionally high income, or other extreme situations. You have to find another way to file your tax returns. You should talk to some local tax professionals and see if one of them is able to prepare your returns.
