Hi, I married my fiance Jan of this year. When I filed for tax this month, I filed as married filing jointly. My wife is a student and does not have income. Now I found out that if I married in Jan, I can't file as married because the tax year only includes up to Dec of last year.

Is it worth it to amend this honest mistake? If I just leave it as it is, will I get penalty fee?

Thank you so much for your input and advice!

Generally there would not be a separate penalty for filing with the wrong status. What would happen is that if the IRS requires you to adjust your filing status, or if you file a 1040X on your own to correct the error, then you would owe penalties and interest on any additional taxes that were due as a result of the change. The penalty would be equal to one half of one percent every month that the tax is underpaid, not to exceed a total of 25% of the additional taxes due. Interest is compounded daily and the interest rate is changed quarterly, but is generally running around 4 to 5% per year.so it is up to you.