You may be able to claim a tax credit for each child you have under the age of 17 if you make under $75,000 if your filing status is single, under $110,000 if married and filing jointly or under $55,000 if married and filing separately. If your income exceeds the amount allowable for your filing status, you may still be eligible for the credit but the amount will be less. In order to claim the credit, the child must be your dependent, your natural child, adopted child, step child, foster child, grandchild, great grandchild, or great great grandchild and must be a US citizen or resident.
To compute this credit, you must use the IRS Child Tax Credit Worksheet. Basically, this sheet will reduce your credit by $50 for each $1,000 that your modified adjusted gross income is over the amount allowable for your filing status. A child tax credit is normally not refundable if it exceeds your taxes.
If you have 3 or more children and the regular child tax credit exceeds your taxes, you may be able to use the Additional Child Tax Credit to get a refund. If you claim the additional child credit, a refund is generated from Social Security and Medicare taxes that were withheld from your pay. To compute this credit, use the IRS Child Tax Credit Worksheet as you would for the regular child tax, then fill out IRS Form 8812, Additional Child Tax Credit. This credit should not be used in combination with the regular child tax credit.