Last year in my income tax I mark single in my status but I’m separate still married

[Critter-3 · Accepted solution]

If you filed an incorrect tax return you are required to amend the return to correct the error ... it may or may not affect the bottom line but it should be filed either way for this situation.  

See this TurboTax support FAQ for amending a tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...

[xmasbaby0]

Yes, you need to amend your incorrect tax return.  If you were still married at the end of that tax year then your filing choices were to file married filing jointly or married filing separately.   Or.....maybe....if you were the custodial parent of the children, Head of Household.   "Single" was not an option if you were legally married.   Better find out how your spouse filed, too.  You both had to file the same way if you file married filing separately.   If one of you used standard deduction then the other one must also; or you both have to itemize.   It cannot be one of each.

If I am filing a separate return why do I have to list my spouse’s information on my return?

Even if you file separate returns (the worst way to file) you each have to list each other's SSN's and some other information on your own tax return.  The IRS can then cross check to make sure you are not "double dipping" for itemized deductions, dependents, etc.

If you are in a community property state, there is more information that will be needed.

Community property states:  AZ, CA, ID, LA, NV, NM, TX, WA, WI