From filing joint to seperate

Sorry---it will not be that simple.   You cannot just switch the filing status and leave everything else as is.   And..are you in a community property state?  It gets even trickier if you are.

Are you using the CD/download or online TurboTax?

It is not easy to compare MFJ to MFS using online TT but you can do it.  Since you only get one return for each account and user ID, you have to use 3 accounts and user ID’s—one for MFJ and two for each of the MFS returns.  Compare, choose, and file—and pay—accordingly.

It is much easier to do this comparison using the desktop version of TT installed from a CD or downloaded to your own computer.  You pay once for the software and you can prepare multiple returns easily, and it has a “what if” feature that allows comparisons.

If you were legally married at the end of 2023 your filing choices are married filing jointly or married filing separately.

Married Filing Jointly is usually better, even if one spouse had little or no income. When you file a joint return, you and your spouse will get the married filing jointly standard deduction of $27,700 (+$1500 for each spouse 65 or older)  You are eligible for more credits including education credits, earned income credit, child and dependent care credit, and a larger income limit to receive the child tax credit. 

If you choose to file married filing separately, both spouses have to file the same way—either you both itemize or you both use standard deduction. Your tax rate will be higher than on a joint return.

 Some of the special rules for filing separately include: you cannot get earned income credit, education credits, adoption credits, or deductions for student loan interest. A higher percent of your Social Security benefits may be taxable. Your limit for SALT (state and local taxes and sales tax) will be only $5000 per spouse. In many cases you will not be able to take the child and dependent care credit. The amount you can contribute to a retirement account will be affected. If you live in a community property state, you will be required to provide additional information regarding your spouse’s income. ( Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI)

 If  you are using online TurboTax to prepare your returns, you will need to prepare two separate returns and pay twice since with online, you get one return per fee.

https://ttlc.intuit.com/questions/1894449-married-filing-jointly-vs-married-filing-separately

https://ttlc.intuit.com/questions/1901162-married-filing-separately-in-community-property-states

https://ttlc.intuit.com/questions/1894449-is-it-better-for-a-married-couple-to-file-jointly-or-separately

As you have seen, TurboTax will not split a joint return into two separate returns. If you are using the CD/Download Desktop TurboTax software, not TurboTax Online, you can use the What-If Worksheet to do an estimate of how separate returns would work out compared to a joint return. After completing your joint return, open the What-If Worksheet in Forms Mode. After you open the form, before you do anything, click on Help Center. In the introductory information at the top of the Help, scroll down a bit until you see the following paragraph.

"If you are preparing a Married Filing Joint vs Married Filing Separate comparison, it is very important that you read preparing a Married Filing Joint Versus Married Filing Separate Analysis."

The underlined part of that sentence is a link. Click on that link in the Help (not here in the Community) and follow the instructions there.

Unfortunately, switching the filing status between joint and separate is likely to cause errors in the tax return that are hard or impossible to fix. To play safe, since you have already switched, you should clear or delete the return you were working on and start over from scratch.

You should also be aware that, because of all the disadvantages that xmasbaby0 listed, it is very rare for filing separately to turn out better than filing jointly.