If you are filing as head of household with one child, with a W-2 for $55,000, and have no other income or deductions, your federal balance due would be approximately $2,100.
Child tax credit, offsets income tax liability and produces this tax result.
Any federal and state withholding listed on W-2 boxes 2 and 17, respectively, would increase your tax refund by those amounts.
Depending on your state, the state refund will differ.