To purchase the download version of TurboTax, you will visit the following TurboTax link: https://turbotax.intuit.com/personal-taxes/cd-download/, and choose the version of TurboTax that you wish to purchase and click on the Buy Now button for that version. Once you have completed your purchase you can follow the instructions listed in the TurboTax FAQ below to download your purchased download:

https://ttlc.intuit.com/replies/3302070

I am preparing a trust return and need to purchase the California state program

I just need the state trust return to finish; this can’t be this difficult?

Just to clarify, are you trying to purchase California State TurboTax alone, without filing a federal return?

The TurboTax state program is designed to transfer information from your federal return. For this reason, TurboTax state isn't sold as a standalone tax-preparation product.

Please click Can I prepare and file just my state return using TurboTax? to learn more. 

California e-file reject: Your principal residence information, county field is case sensitive and o...