Are you referring to the email verification code entered before you can efile? If so, you have to keep that screen open that's asking for the code, while you use a different tab, different window, different browser, or your phone to check your email for the code. If you close that initial screen in order to get the code and try to enter it, it will say the code is invalid or expired. But you can leave it open and use a different tab/window/browser to get the code from your email.
So if you've been closing that screen to get the code, then try again leaving it open using the steps above. If still unsuccessful, here's something else to try.
While logged into Online TurboTax, near the bottom of left column menu go into Intuit Account. Then go to Sign In and Security. See if your email address is correct there, and if so see if it is "verified." If not verified, you can verify it there with the link there. It may then send you a link to that email address to verify with. Once verified for the Intuit Account purposes, close Online TurboTax. And then sign in again. That might be enough to fix it. It may or may not ask you for a code to efile after that. If it does, then retrieve the code and try it, but again...DO NOT close the screen asking for the code.
