I am unable to install the 2018 TurboTax Deluxe as I am getting the error message that I first need to install .NET framework v4.0. How do I do this?

what os on your computer.     if you have the right os and got a legitimate copy of TT .net framework, if needed would be installed when you installed TT.    

first check to see if a version is installed.

in control panel click on programs and features

in the new window click on view installed updates.  

do you see a version of .net framework installed 

if so try this

before clicking in setup icon. make sure you select run as administrator 

you may also need to disable any antivirus program temporarily.

if that still doesn't work go to this website https://dotnet.microsoft.com/download

what os on your computer.     if you have the right os and got a legitimate copy of TT .net framework, if needed,  would be installed when you installed TT.    

first check to see if a version is installed.

in control panel click on programs and features

in the new window click on view installed updates.  

do you see a version of .net framework installed higher than 4.0 That's ok

as i said try running installation as administrator and disable antivirus software until installation complete.  reboot. reactivate antivirus

also you can try this website https://dotnet.microsoft.com/download

you only need the ..netframework runtime.

if that won't install then perhaps the problem is with user account.  if you aren't an administrator or allowed to act as one, software installation may be blocked.   

before clicking in setup icon. make sure you select run as administrator 

you may also need to disable any antivirus program temporarily.

if that still doesn't work go to this website https://dotnet.microsoft.com/download