A married person cannot legally file their taxes as single, and submitting tax returns where your spouse self-designates as single is a HUGE red flag for Immigration. First and foremost, your husband needs to see a CPA to amend his tax returns. That, however, isn't likely to be enough to satisfy USCIS. I would recommend that you seek the counsel of an experienced immigration attorney to protect your interests in this situation.
Answers provided by Ksenia Maiorova, Esq. on Avvo.com are of a general nature and do not constitute legal advice.
You need to be married and living together to qualify under the 3 year naturalization eligibility requirement. If you are not eligible you may consider withdrawing but before you do anything have a confidential consultation with an immigration attorney.
Attorney Robert Brown's (former INS Director, 1972-99) reply to your question is general in nature, and does not constitute legal advice as all facts are known to him. For specific advice or representation you should retain an attorney experienced in immigration law. Mr. Brown's reply on AVVO does not create an attorney/client relationship not constitute legal advice.
Hello hope this message finds you well. Your husband will definitely have to amend his taxes right away. This might not be sufficient prove for USCIS and you might have to supplement your file with affidavits and other evidence. I highly recommend that you have a consultation with an immigration attorney and get help on this issue. Best of luck to you.