Filing Mortgage 1098 requires itemizing both couple filing MFS. Can spouse give 100% of benefit but continue filing with itemized deduction? Software defaults to std ded

Does your spouse realize that all she "gets" if she can claim the 19 year old is the $500 credit for other dependents?  No earned income credit, and no education credit if he is a student--because you do not get EIC or education credit if you file MFS.   And he is too old for child tax credit.

If she does not enter any itemized deductions, she will not even get the standard deduction amount.  She may very well get less, thereby causing more of her income to be taxed.

Married filing separately is usually the worst way to file.  Why do you (or your spouse) want to file that way?

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

The requirement is you both do the same. both take the Standard Deduction 

OR

Both Itemize. 

Here are the instructions to change your selection to Itemize or take the Standard Deduction.

1. Open your tax return and select Federal, then Deductions & Credits.
2. Scroll to the bottom and select Continue.
3. Answer all the questions, until you get to the screen Based on what you just told us, the Standard Deduction is best for you or Based on what you just told us, itemizing deductions is best for you.
4. On that screen, select Change my deduction.
   • You'll see a pop-up showing how much each deduction is worth.
5. If you want to change your deduction, select it and Continue.
6. If you don't want to change your deduction, select Cancel.

@gdizon19063-gmai