To claim the credit, you and your spouse must file a joint return and complete IRS Form 2441. If it is a daycare center, it must be in compliance with state and local regulations. You also must include on the return the Social Security numbers of your children who receive the care. There's no credit without it. Omitting Social Security numbers while still claiming the credit will result in a summary assessment of tax liability against you.
Several limits apply.
First, qualifying expenses are limited to the income you or your spouse earns from work, using the figure for whomever earns less. If one of you has no earned income, you will not be entitled to any credit. Credits are always more valuable than deductions. As you incur dependent care costs, you submit a statement with the plan administrator substantiating the cost to receive reimbursement. Dependent care FSAs are generally more advantageous from a tax perspective than taking the tax credit.