Yes, you may save your work in TurboTax Online then come back and finish later. Just click Sign Out in the lower left corner of the TurboTax Online window (click the screenshot below to enlarge it for reference). TurboTax will save your information and sign you out of your account.
When you're ready to continue working just sign in, click Take me to my return, then click Pick up where I left off.
Can I save my return and come back later? https://ttlc.intuit.com/replies/3301211
