This needs to match how you will file your Taxes in 2018.
If you are single, the answer is 1.
If you are a Family with husband, wife, and 2 young children your answer is 4.
If you are a Family of 7 but 2 of the children file their own taxes and claim themselves as tax exemptions, then the answer is 5.
If you are married, you will want to file jointly if you can qualify for a Health Tax subsidy. (The IRS ruled that married filing separately won't qualify for a Tax subsidy no matter what their income.)
The number in your family should match your 2016 Tax filing.
