I started a new job right after I got married, and I was told when I was filling out my paperwork to claim myself, my spouse, and head of household in order to get the most money back at the end of the year. Now I'm seeing that I don't even qualify to claim HoH and I'm concerned that this will majorly mess with my refund. This is my second year filing taxes on my own, and I don't really know what I'm doing. I'm worried that I'll owe money now.
It is possible that even though you are married you could be considered unmarried at the end of the year.
From IRS Pub 501:
To qualify for head of household status, you must be either unmarried or considered unmarried on the last day of the year. You are considered unmarried on the last day of the tax year if you meet all the following tests.
You file a separate return. A separate return includes a return claiming married filing separately, single, or head of household filing status.
You paid more than half the cost of keeping up your home for the tax year.
Your spouse didn't live in your home during the last 6 months of the tax year. Your spouse is considered to live in your home even if he or she is temporarily absent due to special circumstances. See Temporary absences , later.
Your home was the main home of your child, stepchild, or foster child for more than half the year. (See Home of qualifying person , later, for rules applying to a child's birth, death, or temporary absence during the year.)
You must be able to claim an exemption for the child. However, you meet this test if you can't claim the exemption only because the noncustodial parent can claim the child using the rules described later in Children of divorced or separated parents (or parents who live apart) under Qualifying Child or in Support Test for Children of Divorced or Separated Parents (or Parents Who Live Apart) under Qualifying Relative. The general rules for claiming an exemption for a dependent are explained later under Exemptions for Dependents
The important thing is to file with the correct status when you file your income tax return. If you are married and living with your spouse, then Married Filing Jointly (MFJ) is the choice that you would likely select when you actually file. HoH does not appear to apply to you since you appear to be living with your spouse. Note that the Standard Deduction for MFJ is $24,000 (assumes under age 65 and not blind). The Standard Deduction for HoH is $18,000. Therefore using a withholding table, which would assume an $18,000 deduction instead of the real $24,000 deduction, could result in too much money being withheld from your pay than you would need to have withheld. The effect of the over withholding would result in a higher refund. Getting a higher refund is not a legal problem, but it might not make the most financial sense. Unless you have a complex return, the IRS recommends using their Withholding Calculator for your W-4.