If my husband and I were single last year (so filed individually) but now married, can I import any data from our last years forms?

[xmasbaby0]

To begin a new joint return on TurboTax:

You will not be able to merge two previous TT account to start your new joint return.  You can transfer ONE of your 2020 returns into a new return, so choose the most complicated one.  The other spouse’s information needs to be entered manually.

When you enter your own information in My Info, you have to answer the question "Were you married?"  If you click the button for Married, then a drop down will appear that asks, "Do you want to file this return together with your spouse?"  Then you choose yes to file a joint return.  You would then enter your spouse's information into My Info.  Whenever you are entering income information there should then be a spot for you and for your spouse's income information.  Income screens will have spots with each spouse’s name—be careful to enter under the correct names.

[bluedeb]

You can only transfer one prior years return into the current return.  When filing for the first time as Married Filing Joint, you should transfer the prior year return that has the most information and/or the name you want to show first on the return.  

[Critter-3]

And once you have set the order you will file in for taxpayer and spouse it is highly recommended that you keep the same positions going forward no matter who earns more money ... switching places can cause confusion with the IRS which no one wants to do voluntarily.