See IRS pub 17:
https://www.irs.gov/publications/p17/ch32.html#en_US_2016_publink1000174406
Care Provider Identification Test
You must identify all persons or organizations that provide care for your child or dependent. Use Form 2441, Part I, to show the information.
If you don’t have any care providers and you are filing Form 2441 only to report taxable income in Part III, enter “none” in line 1, column (a).
Information needed. To identify the care provider, you must give the provider's:
Name,
Address, and
Taxpayer identification number.
If the care provider is an individual, the taxpayer identification number is his or her social security number or individual taxpayer identification number. If the care provider is an organization, then it is the employer identification number (EIN). You don’t have to show the taxpayer identification number if the care provider is a tax-exempt organization (such as a church or school). In this case, enter “Tax-Exempt” in the space where Form 2441 asks for the number. If you can’t provide all of the information or if the information is incorrect, you must be able to show that you used due diligence (discussed later) in trying to furnish the necessary information.
Getting the information. You can use
Form W-10 to request the required information from the care provider. If you don't use Form W-10, you can get the information from one of the other sources listed in the instructions for Form W-10 including:
A copy of the provider's social security card,
A copy of the provider's completed Form W-4 if he or she is your household employee,
A copy of the statement furnished by your employer if the provider is your employer's dependent care plan, or
A letter or invoice from the provider if it shows the information.
You should keep this information with your tax records. Don’t send Form W-10 (or other document containing this information) to the Internal Revenue Service.
Due diligence. If the care provider information you give is incorrect or incomplete, your credit may not be allowed. However, if you can show that you used due diligence in trying to supply the information, you can still claim the credit. You can show due diligence by getting and keeping the provider's completed Form W-10 or one of the other sources of information just listed. Care providers can be penalized if they don't provide this information to you or if they provide incorrect information.
Provider refusal. If the provider refuses to give you their identifying information, you should report on Form 2441 whatever information you have (such as the name and address). Enter “See Attached Statement” in the columns calling for the information you don't have. Then attach a statement explaining that you requested the information from the care provider, but the provider didn't give you the information. Be sure to write your name and social security number on this statement. The statement will show that you used due diligence in trying to furnish the necessary information.
