My wife left me and has cut off contact. I don't know how she filed. I own a business and need to itemize / don't know if she filed jointly or claimed HOH. Advice please.

If you are still legally married and you do not qualify to file using the Head of Household filing status, then you will use Married Filing Separate.  File your return with your information to the best of your ability.  If there are issues that arise due to the IRS trying to reconcile your return and your spouse's return, then you will be contacted by mail by the IRS.

Also, if you do not have your spouse's Social Security number to include on your Married Filing Separate return, then you will be required to file your return by mail.  It cannot be sent electronically without that information.  

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