Yes, if you are using TurboTax CD/Download, he can use any returns you have left over.

If you are using TurboTax Online and have the Standard 8 return package, then he can use it to prepare his return, but he must do it in the same account as you used to create yours.

If you are using TurboTax Online but don’t have the Standard 8 return package, then he can create a new return in TurboTax Online, but he will be charged separately. He can also create his own account.