First, we would like you to know we are sorry for your loss.
You are right, you must file separate returns. Spouse's income is used to calculate certain credits on the income tax return for the period they were a couple. This is why the spouse's income may be needed to calculate certain credits.
When you don’t know all the information yet, you just must take a note on the side of the information needed and continue the profile/enter the income. Then you'll do the same for the deceased spouse return. We understand you'll have to navigate from one return to another and this is why we suggest taking note of the missing information you'll need and avoiding to many backs and forth.
Here, on this FAQ you'll find some articles that may helped you.
Thank you for choosing TurboTax.
