My file for tax year 2023 was returned. can I itemize deductions for tax year 2023, even though my husband filed first, separate and only claimed standard deduction?

No.   There is a strict rule.   If you filed married filing separately, you are both required to file the same way.   Both of you must use standard deduction or both of you have to itemize.   If your spouse used standard deduction, then you are also required to use standard deduction.   

The only way your rejected 2023 return can be filed now is by mail; e-filing is closed.

You will need to print, sign and date the return in ink, and mail it.

Go to Tax Home 

Scroll down to Your tax returns & documents.  Click on the Year 2023 and Click on Download/print return (PDF)

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.