I want to see how much my taxes would have changed in 2020 if we married file separately instead of married file jointly? How to do this? program broke when I tried.

[mgh234]

started getting random numbers and things i filled out breaking, and such.

[VolvoGirl]

For 2020?  Do you mean 2021?  Are you using the Online version or the Desktop program?

To compare Joint to MFS. If you are using the Online version, do NOT change anything on your return. You would have to start with a new account and do a test return. You don't have to pay unless you want to print it out. So you might need 3 accounts, one for Joint and two MFS, one for each spouse.

How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-onli...

It would be better to use the Desktop CD/Download program. It can do unlimited returns and has a What If worksheet to compare them and many other advantages over the online version. You can move your current online return to the Desktop program without paying for Online.

You can buy the Desktop CD/Download program here
https://turbotax.intuit.com/personal-taxes/cd-download

If you are using the Desktop program……
You probably will have to fill out 3 new returns. The 2 MFS returns will have different data to enter. Well you could fill out 1 of the MFS returns first (whoever you want to be listed as Primary). Then copy it, go up to FILE - Save As and give it another name and then change it to Joint and add the other spouse to it. Then you have to start a new blank return to do the other spouse's MFS return.

[xmasbaby0]

"....the program broke...."?    What program?

For tax year 2020?   You cannot use the current online software for that.  Online is only for 2021, and the results you would get for 2020 would be all wrong no matter what you do.

If you want to try preparing a 2020 return both ways--jointly and separately---you need the CD/download software for 2020 on a full PC or Mac.

And you have to follow all of the rules for MFS if you prepare separate returns.   If one spouse itemizes, you both have to itemize, even if one of you does not have enough itemized deductions to exceed your standard deduction.   Or you both have to use standard deduction.

You cannot get education credits or earned income credit if you file MFS.

If you have the desktop software for the right tax year you can also use the what if feature 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-filing-status/compare-married-filing...