TurboTax Home & Business 12 returns Desktop version can be downloaded up to 3 computers. You can install it on your friend's computer by logging into your account. You will use your credentials just to download the software.
Make sure to log out of your account afterwards. They will not have access to your Tax returns or another information & vice versa.
You can use TurboTax Online Version next year and pay per return for a single return.
Thanks for choosing TurboTax.
