How can I get TurboTax 2017 & 2018 to open in my iMac w/OS 10.10.5? I can't open either one. The pervious years open just fine.

[mesquitebean]

What do you mean by "open?"   Do you mean "install" or "launch?"

It looks like your OS X version is too low.  2017 TurboTax for Mac requires OS X 10.11 or higher.   2018 TurboTax for Mac requires OS X 10.12 or higher.

FAQ:  System requirements for TurboTax for Mac:

https://ttlc.intuit.com/community/system-requirements/help/minimum-system-requirements-for-turbotax-...

 If you have the CDs, the CD also has the Windows version if you have a PC available.   

Did you recently purchase 2017 and 2018 software to prepare 2017 and 2018 returns?  You can ask TurboTax Support for a refund, or to provide a download for a Windows computer, if you have one.

For a 2018 return, you can still use Online TurboTax.   But you cannot prepare a 2017 return online.

[Geokmcq]

I have a Mac with external cd.  Turbotax does not open.

[Geokmcq]

I have a Mac with external cd.  Turbotax does not open.  I am using 10.15.1

[macuser_22]

@Geokmcq -

if you get the message "TurboTax cannot be opened because Apple cannot check it for malicious software" then that is caused by the Apple "Gatekeeper" introduced with OS X 10.15 (Catalina).

That has nothing to do with TurboTax and will happen for any application not purchased from the Apple Store.

See this Apple article on this: https://support.apple.com/en-us/HT202491

And this TurboTax help article: https://ttlc.intuit.com/community/troubleshooting/help/turbotax-for-mac-won-t-open-when-installed/00...

For older Mac systems when TurboTax will not open.
See:

Be sure that System Preferences -> Security & Privacy -> General -> Allow apps downloaded from App Store and identified developers is checked.

Go to the Applications folder and select the TurboTax application in the Finder and right click with the mouse (or control click) ans select the top "open". That should force the first open. After that it should open normally.

https://ttlc.intuit.com/questions/1899267-administrator-rights-mac