Abul (U.S citizen) married Monika (Korean citizen) in 2016. In 2016, he filed his tax return as single. In 2018, Monika came to U.S.A as a permanent resident and got her social security number. Can Abul amend his 2016 tax return and make married filing jointly to claim more refund?
I an't comment on whether it was correct for you to file single in 2016 but I can tell you that you cannot amend that return to file married now because she did not have the social security number in that year/
You likely filed with the wrong status as 'single' and should have amend the return to the correct the filing status. Follow the rules for filing when married to a non-resident alien spouse. Once your spouse has an ITIN or SSN, you would file using the filing status of Married filing Separately, Head of Household (if qualifying), or Married Filing Jointly if you make the election to treat the spouse as resident alien. You generally have 3 years from the date the return was filed to submit an amended return.