We got married on December 31, can I file for head of household?

You are considered Married as you got married on December 31, 2016.

Your only filing options for 2016 are Married filing Jointly or Married filing Separately. You cannot file Head of Household.

You should file Married filing Jointly as this is the more advantageous option. You can claim your son as your dependent on the joint return.

If you file separately, there are special rules which make you pay more tax in most cases.

Here are the special rules:

If you choose married filing separately as your filing status, the following special rules apply. Because of these special rules, you usually pay more tax on a separate return than if you use another filing status you qualify for.

1. Your tax rate generally is higher than on a joint return.
2. Your exemption amount for figuring the alternative minimum tax is half that allowed on a joint return.
3. You can't take the credit for child and dependent care expenses in most cases, and the amount you can exclude from income under an employer's dependent care assistance program is limited to $2,500 (instead of $5,000 on a joint return). However, if you are legally separated or living apart from your spouse, you may be able to file a separate return and still take the credit. See What’s Your Filing Status? in Pub. 503, Child and Dependent Care Expenses, for more information.
4. You can't take the earned income credit.
5. You can't take the exclusion or credit for adoption expenses in most cases.
6. You can't take the education credits (the American opportunity credit and lifetime learning credit), the deduction for student loan interest, or the tuition and fees deduction.
7. You can't exclude any interest income from qualified U.S. savings bonds you used for higher education expenses.
8. If you lived with your spouse at any time during the tax year:
1. You can't claim the credit for the elderly or the disabled, and
2. You must include in income a greater percentage (up to 85%) of any social security or equivalent railroad retirement benefits you received.
9. The following credits and deductions are reduced at income levels half those for a joint return:
1. The child tax credit,
2. The retirement savings contributions credit,
3. The deduction for personal exemptions, and
4. Itemized deductions.
10. Your capital loss deduction limit is $1,500 (instead of $3,000 on a joint return).
11. If your spouse itemizes deductions, you can't claim the standard deduction. If you can claim the standard deduction, your basic standard deduction is half the amount allowed on a joint return.