from where? there are other authorized sources other than Turbotax so it will depend on them. For practical purposes only 3 years. after that not only will the download not be available but if you had to install the program on another computer no updates would be available and no states would be available. even saving the program on a thumb drive won't help because the updates and states won't be available. save a copy of your return as a pdf offline like on a thumb drive, cd or DVD.
